[3E01-03] Corrosion and Electrochemistry in PWR

[3E02] Analysis of Corrosive Environment in the Primary Coolant System of PWR

*YOICHI WADA¹, Toshimasa Ohashi¹, Ryosuke Shimizu², Makoto Nagase², Shinobu Okido² (1. Hitachi, 2. HGNE)

Keywords:PWR, Primary coolant system, Corrosive environment, Radiolysis, Electrochemical corrosion potential

A radiolysis and electrochemical corrosion potential (ECP) calculation model has been developed to evaluate corrosive environment in the primary cooling system of the PWR. Alpha-rays and neutrons promoted radiolysis of water and high pH promotes recombination reaction at high DHs. Hydrogen peroxide concentration levelled off at 1 ppb above 5 mL kg⁻¹ DH in the in-reactor region. If calculated oxidant concentrations and diffusion layer thickness were assumed to have an error by factor of 2, ECP model could reproduce ECPs measured in the PWR-simulated test reactor as a function of DH. After this, by establishing input parameters for the dedicated models, the accuracy of the models will be improved for practical use adequately.