Regulatory Activities on Steam Generator Tubes in Korean Nuclear Power Plants

Abstract

To date 20 nuclear power plants are in operation and 4 plants are construction in Korea. Among these plants Kori unit 1 has been operating commercially for 28 years and replaced their steam generators, having 11.5% plugging rate as an average value, to delta 60 ones in 1998. The causes of tube plugging were various: for example, pitting, primary and secondary stress corrosion cracking, sleeve bulging, preventive plugging, and so on. At present major concerns of domestic steam generators are ODSCC and PWSCC in roll transition region, fretting wear in upper support structures, and wear and deformation damage by foreign objects. In this presentation, an overview of the repair history, operating experiences and inspection methods of steam generator tubes in Korean nuclear power plants is introduced. Also regulatory activities and strategy on steam generator management are presented.