[en] The transmission Moessbauer spectroscopy has been used in the investigation of magnetic phases of corrosion products of nuclear power plant V-1 (Jaslovske Bohunice) steam generator and secondary circuit pipelines. The corrosion layers were separated by scraping of the rust from the surface and the powder samples were studied. It should be noted that the gamma spectroscopic measurements give no evidence of the presence of low-energy gamma radiation emitted from the samples. It was confirmed that cracks occur on the former feed water-distributing system. Defects were observed mainly in the area of feed water collector T-junction where DN250 nozzle is connected to the feed water distribution piping in the steam generator compartment. Design changes performed in the Bohunice steam generators in 1994 seem to be the proper answer for the corrosion limitation. According to the results obtained from the Moessbauer spectra analysis, it is possible to establish that main components of secondary circuit's corrosion products are magnetite (Fe₃O₄) and hematite (α-Fe₂O₃). The results can be used for the optimal maintenance of VVER-440 nuclear reactors. (author)