General Correlative Studies, Operation Bren

Book excerpt: A summary of the utilization of the Health Physics Research Reactor and a Co Co60 source during Operation BREN has been prepared, and the pertinent meteorological data have been tabulated. Normalization factors for air dose, as it depends on air density and reactor power level, are obtained as a function of source height; typical dose vs. distance curves are presented. For a source height of 1125 ft and with the detector at the surface of the ground, the relaxation length in air is 230 yards for neutrons from the reactor, 311 yards for gamma radiation from the reactor (including gamma rays from inelastic interactions by neutrons in air), and 256 yards for the gamma rays from Co60. These reduce to 181, 245, and 200 yards, respectively, at 760 mm Hg pressure and 0 deg. C. This is the third of a series of Operation BREN reports and the first concerning experimental results.