FALLOUT OF TRANSURANIUM ELEMENTS FOLLOWING THE CHERNOBYL ACCIDENT

The deposition of transuranium elements in Sweden following the Chernobyl accident was investigated through the analysis of carpets of lichen- and moss-samples and also air-filters and precipitation. The impact of transuranium elements was small compared to that of radiocesium. The deposition of Pu-239+240 was, as for other actinides, inhomogeneously distributed and ranged from 0.1% to 100% of the inventory in 1986 from nuclear detonation tests. The activity ratio of Pu-239+240/Cs-137 was between 10(-3) and 10(-6) in comparison to 10(-2) for nuclear test fallout. The activity ratios of Pu-241, Cm-242, Pu-238, Am-243+244 and Pu-239+240 were about 86, 14, 0.47, 0.14, and 0.13 respectively, but large variations were observed. The results from Sweden were compared with those found in South Finland, Denmark and Southern Europe. The deposition over Scandinavia originated from the initial explosion at Chernobyl, which contained relatively higher amounts of actinide elements than the second emission, which occurred a few days later and was a result of actions taken to bring the fire under control.