Thread Content
I. Typical international cases of corrosion in water-cooled reactors: The Davis-Besse nuclear power plant incident in the United States. Type of corrosion: Stress corrosion cracking in the penetrations of the reactor pressure vessel head. Consequences of the incident: A large amount of boric acid was released, causing a large hole to form in the pressure vessel head; the reactor had to be shut down for extended repairs, resulting in high maintenance costs. Incident at the French Burry-3 nuclear power plant: Type of corrosion – stress corrosion cracking in the penetrations of the control rod drive mechanisms at the top of the reactor pressure vessel. Consequences of the incident: A penetrating leak occurred, resulting in the leakage of primary loop coolant; this forced an emergency shutdown of the unit for inspection. VC Summer nuclear power plant incident in the United States: Type of corrosion – stress corrosion cracking at the dissimilar metal welds in the primary circuit main pipes. Consequences of the incident: a significant leakage of boric acid, which directly compromised the integrity of the primary circuit pressure boundary, leading to special inspections for nuclear safety reasons. The Civaux nuclear power plant incident in France: Type of corrosion – corrosion cracking of welds in primary circuit pipes. Consequences of the incident: a coolant leak occurred, but no serious accident resulted due to timely action; this incident exposed material defects in early European pressurized water reactors. II. Typical cases of corrosion in domestic water-cooled reactors: In early pressurized water reactor units in China, such as those at Daya Bay and Qinshan Phase I, stress corrosion leakage incidents occurred multiple times in the components located on the top of the reactor pressure vessels. Subsequent ten-year overhauls involved the replacement of these components, with new parts made from Inconel 690 alloy, which possesses superior resistance to stress corrosion, thereby completely eliminating this type of corrosion risk.