The effect of zinc addition to pressurized water reactor (PWR) primary water on primary water stress corrosion cracking (PWSCC) susceptibility of mill-annealed Alloy 600 (UNS N06600, 600MA) was examined at 360°C using slow strain rate technique (SSRT). In addition, the influence of oxide films, which were formed beforehand over a long exposure period in the simulated PWR primary chemistry, was examined. To clarify the effect of zinc addition on the characteristics of the oxide films formed on Alloy 600MA and prefilmed Alloy 600MA, oxide film structures and chemical compositions also were examined using Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), and x-ray diffractometry (XRD) techniques. An alternating current (AC) impedance study was conducted to examine the stability of the oxide film. SSRT and AC impedance test results showed that > 10 ppb Zn addition to the simulated PWR primary water reduced PWSCC susceptibility and increased the polarization resistance of the oxide film formed on Alloy 600MA and prefilmed Alloy 600MA. AES, XPS, and XRD studies showed that a double-layered oxide film was formed on Alloy 600MA in the simulated primary water. The outer layer was composed of nickel ferrite (NiFe2O4), and the inner layer of nickel chromite (NiCr2O4) spinel. With the addition of zinc at approximately the 10-ppb level in solution, the outer inverse spinel structure was diminished, and the film was thinner. Even though a double-layered prefilm was formed on Alloy 600MA, the outer inverse spinel oxide was reduced, and zinc was incorporated into the inner spinel oxide of NiCr2O4 by the addition of 10 ppb Zn in the simulated PWR chemistry. A good correlation was observed between PWSCC susceptibility and chromium content in the oxide, even when an oxide prefilm was formed on Alloy 600MA. Based on these observations, it appeared that zinc addition to the simulated primary coolant enhanced the formation of a stable oxide film composed of a zinc-chromium phase. It thereby improved PWSCC resistance of Alloy 600MA, even when a surface oxide prefilm was formed before zinc addition.
Skip Nav Destination
Article navigation
1 June 2000
Research Article|
June 01 2000
Inhibitory Effect of Zinc Addition to High-Temperature Hydrogenated Water on Mill-Annealed and Prefilmed Alloy 600
H. Hirano;
H. Hirano
*Central Research Institute of Electric Power Industry, Komae Research Laboratory, 2-11-1, Iwado-kita, Komae-shi, Tokyo 2018511,
Japan
.
Search for other works by this author on:
S. Shirai;
S. Shirai
**Hokkaido Electric Power Co., Inc., Facilities Management Sec., Nuclear Power Dept., Higashi 1-2, Ohdori, Chuo-ku, Sapporo 060-8677,
Japan
.
Search for other works by this author on:
T. Matsunaga;
T. Matsunaga
***The Kansai Electric Power Co., Inc., General Office of Nuclear and Fossil Power Production, 3-3-22, Nakanoshima, Kita-ku, Osaka 530-8270,
Japan
.
Search for other works by this author on:
K. Yamaoka;
K. Yamaoka
****The Shikoku Electric Power Co., Inc., Ikata Nuclear Power Station, Maintain and Repair Section, 2-5, Marunouchi, Takamatsu, Kagawa 796-0421,
Japan
.
Search for other works by this author on:
K. Oshinden;
K. Oshinden
*****The Kyushu Electric Power Co., Inc., Genkai Nuclear Power Station, 2-1-82, Watanabe-Dori, Chuo-ku, Fukuoka 847-1441,
Japan
.
Search for other works by this author on:
H. Takiguchi
H. Takiguchi
******The Japan Atomic Power Co., Inc., Plant Management Headquarters, Plant Engineering Dept., 1-6-1, Otemachi, Chiyoda-ku, Tokyo 100-0004,
Japan
.
Search for other works by this author on:
Online ISSN: 1938-159X
Print ISSN: 0010-9312
NACE International
2000
CORROSION (2000) 56 (6): 623–637.
Citation
H. Kawamura, H. Hirano, S. Shirai, H. Takamatsu, T. Matsunaga, K. Yamaoka, K. Oshinden, H. Takiguchi; Inhibitory Effect of Zinc Addition to High-Temperature Hydrogenated Water on Mill-Annealed and Prefilmed Alloy 600. CORROSION 1 June 2000; 56 (6): 623–637. https://doi.org/10.5006/1.3280565
Download citation file:
