Concentrations of krypton-85 near the Nevada Test Site

Since 1972, the Environmental Monitoring Systems Laboratory has operated a network of noble gas samplers around the Nevada Test Site (NTS). For 10 of those years, the network also included several samplers on the NTS. The network was established to measure the concentrations of noble gases released to the atmosphere by underground nuclear detonations, by post-test operations, and by seepage from the ground from previous underground tests. During this 12-year period, the concentrations of krypton-85 measured in samples collected around the NTS gradually increased with time from 16 pCi/m3 in 1972 to 25 pCi/m3 in 1983. This increase was not found to be due to nuclear testing activities at the NTS but to the world-wide use of nuclear technology, a trend that has been predicted by previous investigators. The observed trend of increasing concentration was considerably less than had been projected by other authors, being only one-eighth to one-fifth of that projected. It is suggested that the difference from predictions is due to a decrease in the rate of growth in the number of nuclear power plants and, more significantly, the slow growth of nuclear duel reprocessing activities