Optimization of dissolved hydrogen concentration for mitigating corrosive conditions of pressurized water reactor primary coolant under irradiation (1) evaluation of water radiolysis

• Published in: Journal of Nuclear Science and Technology Vol. 61; no. 4; pp. 448 - 458
• Main Authors: Hata, Kuniki, Hanawa, Satoshi, Chimi, Yasuhiro, Uchida, Shunsuke
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo Taylor & Francis 02.04.2024; Informa UK Limited; Taylor & Francis Ltd
• Subjects: Alpha rays; Anodic polarization; Boiling water reactors; Coolants; Corrosion effects; Corrosion potential; Electrochemical corrosion; electrochemical corrosion potential; Hydrogen; Hydrogen peroxide; INCA loop; Irradiation; Parameters; Pressurized water reactors; primary coolant; PWR; Radiolysis; Stress corrosion cracking; Water chemistry
• ISSN: 0022-3131; 1881-1248
• DOI: 10.1080/00223131.2023.2239810

A major subject for evaluating the corrosive conditions in the pressurized water reactor (PWR) primary coolant is to determine the optimal hydrogen concentration for mitigating primary water stress corrosion cracking (PWSCC) without adverse effects on major structural materials. An analytical method combining water radiolysis and electrochemical corrosion potential (ECP) analyses was proposed for evaluating the corrosive conditions in PWR primary coolant. These procedures originally developed for boiling water reactors (BWRs) were successfully extended to PWRs with different water chemistry parameters, including pH, temperature, and radiation qualities, after minor changes in the original procedures and major input parameters, such as the inclusion of the effects of alpha radiolysis and Li + (Na + ) and H + effects for the anodic polarization curve. This study discusses the results of water radiolysis analysis for PWR primary coolant, and the characteristic behavior of hydrogen peroxide (H 2 O 2 ) as a function of hydrogen inlet concentrations in PWR primary coolant conditions (higher pH and α-ray irradiation). A possible reaction scheme involving e aq - was proposed for H 2 O 2 suppression under alkaline conditions. The corrosive conditions were discussed in the following publication, using ECP as the major index for PWR corrosive conditions.