Database development on SCC from a retired steam generator

Stress corrosion cracking (SCC) in Korean Steam generator(SG) tubings had been serious problems because the tubes were made of low temperature mill annealed alloy 600, which is known as relatively SCC susceptible in PWR environment. After experiencing various corrosion problems such as pitting, wastage, denting, primary side stress corrosion cracking (PWSCC), out side diameter stress corrosion cracking(ODSCC), the SGs were replaced in 1998 with a new one. A metallographic examination on the defected tubes could be utilized for setting up a guide line for a safe operation of the SG. A destructive analysis on 91 tube sections was carried out, and a database was developed during a 5 year research work. The objective of the present paper is to demonstrate the SCC location in terms of top of tube sheet(TTS) or tube support plate(TSP), and to seek a relationship between the crack location and corrosion environment at the TTS or TSP regions