Development of a scratch electrode system in high temperature high pressure water

• A rapid scratch electrode system in high temperature water has been built.
• Repassivation kinetics of Alloy 690 was studied in high temperature water.
• The slope of log i(t) vs. 1/Q(t) shows stress corrosion cracking susceptibility.

The scratch electrode system in high temperature high pressure (HTHP) water has been built. The design temperature and design pressure of this system are 350 °C and 20 MPa respectively, and the maximum scratch speed is 3.3 m/s. By using this scratch electrode system, the repassivation kinetics of Alloy 690 in high temperature pressurized water with different dissolved hydrogen (DH) at 300 °C is studied. The research results justify that the scratch electrode system is valid and the scratch technique in HTHP water is a new effective and reliable method to study the SCC susceptibility of nuclear materials.