Retrospective estimation of the concentration of 241Pu in air sampled at a Belgrade site following the Chernobyl accident

The surface air activity concentration of 241Pu for the period May 01–15, 1986, for a monitoring site in Vinča, Belgrade was retrospectively estimated. The results were obtained by re-measurement of plutonium fraction alpha-spectrometric sources, with 236Pu as a tracer, used almost 13 years earlier for the determination of 239,240Pu concentration in surface air immediately after the Chernobyl accident. The estimated 241Pu concentration, based on the 241Am in-growth method for air samples, ranged from 240 to image. The average activity ratio 241Pu/239,240Pu originating from the Chernobyl accident at Belgrade site was approximately 100 at the collection time.