Mandatory safety-related design requirements for this type of equipment include essentially the absolute leak-tightness of the heat exchange surfaces separating sodium from water and the prevention of violent sodium-water reactions. After briefly recalling the various situations likely to give rise to leaks, their evolution (self-wastage), and consequences (wastage and secondary ruptures), the precautions taken during steam generator (SG) designing, manufacturing, and operating phases to minimize leak hazards and satisfy the mechanical design basis requirements adopted for secondary loop components are analyzed. The in-service monitoring systems provided (hydrogen detection, acoustic detection) and the means devised to keep leak consequence within acceptable limits (rupture disks) are described. The automatic or operator-controlled actions initiated by signals from these systems are reviewed (reactor shutdown, SG isolation pressure relief, cooling and inertization of sodium or water-steam circuits). Plant overhaul procedures, servicing operations on the SG itself (whipping tube localization, damage assessment on adjoining tubes by insertion of an eddy-current probe, removal of damaged tubes) and on the secondary loop after detection and prior to restartup are presented. For each device and situation mentioned, a comparison is drawn, underlining the fundamental differences existing in the different types of SGs and tube materials.