Evaluation of effectiveness of SCC prevention technologies after long term operation at the Fugen Power Station

Yuasa, Toyotaka; Abe, Teruyoshi; Nakamura, Takahisa; Myochin, Munetaka; Takagi, Hisatsugu 

Suffered SCC (stress corrosion cracking) at the primary cooling system in 1980, the Fugen power station introduced the three preventive technologies immediately. After the upgrade of the plant, no SCC occurred during the operation period. We have inspected the actual structural materials of the Fugen power station on its decommissioning stage to evaluate effectiveness of SCC management technologies, which are combining material replacement, induction heating stress improvement (IHSI) to reduce the welding residual tensile stress, and application of hydrogen addition to reduce oxygen in the water. No crack in the materials was found by metallurgical structure observation. Moreover, judging from the analysis of residual stress and the heat affected zone in the materials, the effectiveness of SCC management technologies was verified.