Environmental factors causing pipe cracks and degradation in primary system components—KWU steam generator experience

The tubes in steam generators of nuclear power plants with pressurised water reactors form the link between the active primary circuit and the secondary steam water circuit. The integrity of the tubes is therefore a mandatory requirement for a safe operation. This can be met by a careful design of the steam generators as well as the whole secondary circuit by an appropriate selection of the structural materials and by a deliberate control of the water chemistry. The operating experience with KWU steam generators confirms the present and the future steam generator concept followed by KWU.