DOSE-ATTENUATION VARIATION WITH INCIDENT GAMMA-RAY ENERGY IN TWO-LEGGED CONCRETE AND STEEL DUCTS
Technical rept. Dec 1964-Oct 1965
NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA
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Gamma-ray dose-attenuation factors were measured in concrete and steel ducts. For concrete, 3-foot-square and 11-inch-square ducts were used with Au198 0.412 Mev, Cs137 0.662 Mev, and Co60 1.25 Mev gamma -ray sources. Attenuation factors for given geometries were compared as a function of incident gamma-ray energy. The relative effectiveness of steel and concrete ducts of a given geometry was determined. The attenuation factor decreases monotonically with increasing energy in concrete ducts. In the 11-inch steel duct the attenuation factor for the high-energy source Co60 was greater than for the low-energy source Cs137. In comparing the 11-inch concrete and 11- inch steel ducts, it was found that dose rates in the concrete duct were higher by a factor of about 2. Measured attenuation factors were compared with values obtained using a computer code based on the albedo concept. It was found that calculated attenuation factors agree to within or -30 of the measured attenuation factors.
- Nuclear Radiation Shielding, Protection and Safety