Optimization of dissolved hydrogen concentration for mitigating corrosive conditions of pressurised water reactor primary coolant under irradiation (2) evaluation of electrochemical corrosion potential

ABSTRACT

One of the major subjects for evaluating the corrosive conditions in the PWR primary coolant was to determine the optimal hydrogen concentration for mitigating PWSCC without any adverse effects on major structural materials. As suitable procedures for evaluating the corrosive conditions in PWR primary coolant, a couple of procedures, i.e. water radiolysis and ECP analyses, were proposed. The previous article showed the radiolysis calculation in the PWR primary coolant, which was followed by an ECP study here. The ECP analysis based on a couple of a mixed potential model and an oxide layer growth model was developed originally for BWR conditions, which was extended to PWR conditions with adding Li⁺ (Na⁺) and H⁺ effects on the anodic polarization curves. As a result of comparison of the calculated results with INCA in-pile-loop experiment data as well as other experimental data, it was confirmed that the ECPs calculated with the coupled analyses agreed with the measured within ±100 mV discrepancies.

Graphical abstract

KEYWORDS:

• PWR
• primary coolant
• radiolysis
• electrochemical corrosion potential
• anodic polarization curve
• cathodic polarization curve
• INCA loop

Acknowledgments

The authors express their sincere thanks to Dr. Hideki Takiguchi, JAPC-retired, for his kind guidance to evaluate PWR water chemistry from the viewpoint of plant utility.

Disclosure statement

No potential conflict of interest was reported by the author(s).