Assessment of regularities of ground-level air radionuclide contamination at the Russian coast of the Baltic Sea in the course of the long-term Leningrad Nuclear Power Plant (1983-1999) operation

Long-term results of ground-level radionuclide contamination at the Russian coat of the Baltic Sea (nuclear facilities in the vicinity of the town Sosnovy Bor) are under consideration. As compared with 1992-1997, the Leningrad Nuclear Power Plant (NPP) equipment hermetic sealing (in 1998-1999) caused both the reduction of detection frequency of 131I aerosol and the maximum concentrations of 137Cs in the ground-level at the NPP site. Long-term weekly nuclides' concentration time series were examined by correlation analysis. Results of the analysis are presented. The seasonal fluctuations of 7Be concentrations in the ground-level air were examined by the harmonic (Fourier) analysis. The seasonal fluctuations of its concentrations with the maximum in spring-summer period are shown. (author)