“…The integrity of the U-tubes of a SG may be challenged because of the high temperature and pressure conditions of the primary circuit. Consequently the U-tubes are subjected to a great variety of degradation processes (primary water stress corrosion cracking, outside diameter stress corrosion cracking, fretting, pitting, denting, high-cycle fatigue, wastage, etcetera) that can lead to tubes fissure, wall thinning, and potential leakage or finally rupture [MacDonald, 1996]. During the last years considerable efforts have been spent to understand and predict these degradation processes; however SGs steam leakage incidents have continued taken place.…”