RADIOACTIVE INVENTORIES FROM THE KYSHTYM AND KARACHAY ACCIDENTS - ESTIMATES BASED ON SOIL SAMPLES COLLECTED IN THE SOUTH URALS (1990-1995)

The implementation of the nuclear programme in the Cheliabinsk region in the Ural, where plutonium for the first Soviet nuclear weapons was produced, involved radioactive contamination of the environment. The e nd of the cold war in the late 1980s initiated a fruitful co-operation between Russian and Western radioecologists. The present study is a j oint Russian-Ukrainian-Danish effort to make an independent estimate o f the inventories of Sr-90, Cs-137 and Pu-239,Pu-240 from two major co ntamination events in the South Urals, namely, the Kyshtym accident in 1957 and the Karachay wind dispersion in 1967. The calculations are b ased upon deposition measurements of the radionuclides carried out on soil samples assuming that the depositions decreased exponentially wit h distance from the two sources. The inventory estimates are compared with the available Russian information on the two accidents. (C) 1997 Elsevier Science B.V.