A nuclear incident at a power plant in Sosnovyy Bor, Russia

Several radionuclides were identified in the surface air in Finland following a nuclear incident in Sosnovyy Bor on 24 March 1992. In addition to gases, the release contained small uranium fuel particles. The radionuclide concentrations were of the same order of magnitude as the concentrations detected in Northern Finland in 1987 after the nuclear explosion in Novaya Zemlya (1 mBq m-3) but five orders of magnitude smaller than the concentrations during the Chernobyl accident in 1986. The radiological consequences in Finland were insignificant. However, studies show that even a minor release, across the sea and more than 100 km away, can be detected and important information, including the time of the incident and the composition of the release and the burn-up of the damaged fuel, can be revealed by the most accurate radioactivity measurements.