Radioactive tungsten in the atmosphere

As a result of thermonuclear tests carried out by the United States in 1958, radioactive tungsten isotopes W181 and W185 appeared in the atmosphere. Determination of the W181 and W185 concentrations by means of a ψ -spectrometer and β -counter, respectively, made it easily possible to determine the date of formation of these products. The geographic distribution of the radioactive tungsten concentrations is basically the same as that of fission fragment products but the residence time of tungsten in the stratosphere was found to be much shorter than that of fission fragment products. This may be due to the size and weight of the aerosols from which tungsten was deposited. The total activity of the radioactive tungsten ejected into the stratosphere was estimated at 900 MCi.