Abstract
The article deals with the real defect, a crack that occurred on a part of the steam pipeline of the separator and the steam superheater of the turbo-generator in the V2 nuclear power plant (NPP) in Jaslovské Bohunice. The damage was caused by the mechanism of erosion-corrosion, which led to a reduction of the pipe wall with the critical thickness. The main cause of the failure was identified to be the usage of unsuitable steel, instead of the required steel EN 10028-2, during the reconstruction of the pipeline.