Effects of Environmental Factors on the IGSCC Susceptibility of Sensitized SUS 304 Stainless Steel in High Temperature Water

Ohnaka, Noriyuki; Shoji, Saburo; Kikuchi, Eiji; Minato, Atsushi; Ito, Hisao

doi:10.3323/jcorr1974.32.4_214

Cited by 5 publications

(6 citation statements)

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“…The injected agent or by-products may affect corrosion of fuel cladding or the SCC of structural materials. 9,11) Additionally, they may affect plant systems such as the reactor water clean up system (RWCU), off-gas system and condensate system. Reducing agents which cause minimal side effects are desirable.…”

Section: Concept Of the New Mitigation Methodsmentioning

confidence: 99%

Hydrazine and Hydrogen Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors, (II)

Ishida

Wada

Tachibana

et al. 2006

Journal of Nuclear Science and Technology

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Hydrogen and hydrazine co-injection into a boiling water reactor was considered as a new mitigation method of stress corrosion cracking. To confirm decrease of electrochemical corrosion potential by the reduction of oxygen and hydrogen peroxide in bulk water using reducing agent, reaction of hydrazine with oxygen or hydrogen peroxide under simulated downcomer conditions (temperature: 280 C, duration: 4.2 s and gamma-irradiation) was examined. All the oxygen was consumed above the equivalent concentration for the reaction with oxygen within this short time (gammairradiation case) and almost all the hydrogen peroxide was consumed. Reaction rates were accelerated more than five times by gamma-irradiation in each case. Reaction rates with oxygen were compared with other reducing agents such as hydrogen, methanol and ammonia. From the viewpoint of reaction rate and formation of by-product, hydrazine was the most suitable agent. Using a simple model based on the experimental results, water chemistry for the bottom region was calculated for the case of no hydrogen injection and for the case of 0.2 mmolÁkg À1 hydrogen injection into feed water. For both cases, concentrations of dissolved oxygen and hydrogen peroxide were estimated to decrease enough to mitigate SCC, with concentration of ammonia suppressed below the management criteria for reactor water chemistry.

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Section: Concept Of the New Mitigation Methodsmentioning

confidence: 99%

Hydrazine and Hydrogen Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors, (II)

Ishida

Wada

Tachibana

et al. 2006

Journal of Nuclear Science and Technology

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“…Under the crevice condition, the IGSCC mean failure time in the constant load test has been reported to be shorter than that without any crevice [5]. Therefore, there is still room for further study on the CC behavior in high-temperature water under irradiation, especially as an IGSCC initiation site.…”

Section: Introductionmentioning

confidence: 94%

Effects of local radiolysis and geometric parameters on intergranular attack caused by crevice corrosion

Watanabe

Wada

Ishida

et al. 2014

Journal of Nuclear Science and Technology

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Effects of γ -ray irradiation upon crevice corrosion (CC) of type 316L stainless steel (316L SS) as an initiation site of stress corrosion cracking in a boiling water reactor environment have been studied using a material corrosion test loop which could be irradiated with a 60 Co γ -ray source during testing. The CC tests were conducted using crevice specimens with various sizes of crevice gaps. Many of the examined specimen surfaces exhibited a selective grain boundary dissolution; that is, intergranular attack (IGA) as a result of the CC when the crevice gap size was lower than a certain value. The IGA initiation time was shortened by the γ -ray irradiation. The IGA occurred mostly near the crevice mouth at a distance of less than 2 mm from the mouth edge. When γ -ray exposure had occurred, it was found that the number of IGA sites deeper in the crevice increased compared with the IGA site distribution under the no-irradiation condition. Since the electrochemical corrosion potential inside crevice specimens must be low under the conditions for which IGA could occur, it was assumed that γ -ray irradiation accelerated the corrosion rate of 316L SS by decreasing the Fe 2 + surface activity inside the crevice or increasing the cathodic current of radiolytic oxidants on the crevice surface. It was concluded that γ -ray irradiation affects the IGA occurrence not only temporally but also spatially.

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“…o16 The stability of the oxide films on stainless steels and their ability to undergo breakdown and repassivation has been recognized as one of the most important factors in the nucleation and propagation of stress corrosion cracks in type 304 SS in high-temperature water where cracking has been attributed to a mechanism based on film rupture and localized anodic dissolution."'" However, relatively few data are available pertaining to a correlation of SCC behavior of 304 SS with the composition and structure of the oxide film present, e •' [8][9][10][11][12][13][14][15][16][17][18][19][20][21] or to comparisons of susceptibility assessed by different test procedures.…”

Section: Introductionmentioning

confidence: 99%

A Comparison of U-bend and Slow Strain Rate Procedures for Assessing the SCC Resistance of Type 304 Stainless Steel in High-Temperature Water

et al. 1991

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The effects of temperature, chloride content, and dissolved oxygen content on the susceptibility to stress corrosion cracking (SCC) of type 304 stainless steel in high-temperature water have been investigated. Both U-bend and slow strain rate stress corrosion tests were performed, complemented by electrochemical polarization curve measurements and extensive oxide film analyses by Auger electron spectroscopy (AES). The U-bend data showed decreasing susceptibility to cracking with increasing temperature, which correlated with thicker oxide films and greater enrichment of chromium in the films. In contrast, the slow strain rate tests (SSRTs) indicated maximum susceptibility to cracking at 250°C in the temperature range 200 to 300°C and the susceptibility to cracking increased with increasing oxide thickness. The extent of chromium and nickel enhancement in the oxide layers were different for the two specimen types tested in equivalent environments. Greater enhancement of nickel occurred in films formed on SSRT specimens than on U-bend specimens. It is concluded that the choice of test procedure for acquiring accelerated test data may be influenced by whether the components to which the data will be applied are likely to experience plastic strain during use.

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Effects of Environmental Factors on the IGSCC Susceptibility of Sensitized SUS 304 Stainless Steel in High Temperature Water

Cited by 5 publications

References 0 publications

Hydrazine and Hydrogen Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors, (II)

Hydrazine and Hydrogen Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors, (II)

Effects of local radiolysis and geometric parameters on intergranular attack caused by crevice corrosion

A Comparison of U-bend and Slow Strain Rate Procedures for Assessing the SCC Resistance of Type 304 Stainless Steel in High-Temperature Water

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