Continuous Point Source Plume Behavior Out to 160 Miles

Abstract

In order to study the behavior of the plume emitted from the air-cooled nuclear reactor at Brookhaven National Laboratory on central Long Island, radioactive argon-41 has been measured by an airborne gamma-ray spectrometer as far as 160 n mi downwind on a day with neutral stability. A vertical cross section at 144 n mi, obtained by a vertical ?saw-tooth? sampling technique, shows the plume to be well organized with a nearly uniform vertical distribution to at least 2000 ft. The peak concentration, when corrected for radioactive decay, decreases by about a factor of 7?10 over a distance of 150 n mi and a travel time of 10?12 hr. The lateral standard deviation of the plume appears to fit an extension of the Pasquill-Gifford ?D? curve with distance, where σy (n mi) is approximately equal to two-thirds of the travel time in hours.