The present study is an application of the long range transport and dose model TRADOS developed jointly by the Finnish Meteorological Institute and Technical Research Centre of Finland. The aim of the study is to assess the radiation risk in Finland due to the nuclear power plant at Sosnovyj Bor near St. Petersburg in Russia. Probabilities of reaching different parts of the country, transport time and time spent over Finland by the trajectories are presented. Also breadth of the radioactive cloud and incidence of rain are estimated. The calculated radiation doses are based on one single hypothetical release, in which all noble gases are released, together with 10 % of easily vaporizing elements and 1 % of others. All results are based on the assumption that the probability of the release is 100 %. The dose pathways calculated are cloud gamma, fallout gamma, inhalation, and ingestion of milk, meat, green vegetables, grain and roots. External dose rates have been calculated. The necessity of countermeasures and the ratio of the avertable dose to the costs are also assessed. (13 refs., 156 figs., 12 tabs.).