Stress corrosion cracking of pressurized boundary materials of 600 MW nuclear power plant. The critical potential for SCC of SG tubing alloy inconel-690 in simulated secondary water

The experimental method of slow strain rate tests (SSRTs) with constant applied electrochemical potential (ECP) was applied first time on steam generator (SG) tubing alloy In-690 to investigate the relations between stress corrosion cracking (SCC) behavior and ECP in simulated secondary water chemistry condition: 260 degree C, 1 x 10-6 Cl- un-deaerated water. The critical potentials (Ec) for SCC have been determined finally. SSRTs with constant ECP experiments were performed on SERT-5000 dP 9H tension tester, in all tests the nominal strain rate was 4.2 x 10-6/s. Anodic polarization was conducted on high temperature electrochemistry testing autoclave with a model 350A corrosion measurement system, with potential scanning rate 0.3 mV/s. The experimental materials were alloy In-690 provided by Sumitomo of Japan and Vallurac of France