Corrosion of Alloy 690 in Simulated Steam Generator Crevices: Effect of Applied Potential, pH and Pb Addition

Betova, Iva; Bojinov, Martin; Ikäläinen, Tiina; Saario, Timo; Sipilä, Konsta

doi:10.1149/1945-7111/ac4f26

Cited by 8 publications

(1 citation statement)

References 28 publications

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“…Hence, the authors concluded that organic acids (possibly from morpholine decomposition) resulted in corrosion. In another study, alloy 690 (including 61.8 wt% nickel) showed nickel dissolution in simulated steam generator crevices with a pH278=5.2 [54], further proving the obtained results of this work. We emphasize that the calculated E-pH diagrams are for pure nickel and alloy behaviour may be different.…”

Section: Resultssupporting

confidence: 82%

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Khollari¹,

Zebardast

Asselin

2023

Preprint

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Nuclear power plant steam generator (SG) tubes contain nickel as the main alloying element and there is concern about their corrosion. We optimized models for calculating the high-temperature and high-pressure thermodynamic properties of common nuclear alloy elements and then, calculated the E-pH diagrams for nickel in different concentrations of ammonia or acetate ion between 100 to 260 ℃ at 4.7 MPa. This information is used to predict the corrosion behaviour for nickel in the secondary circuit conditions of CANDU SGs. Based on the results, nickel ammonia and nickel acetate complexes are not stable at low concentrations of ammonia or acetate ion. However, increasing the ammonia or acetate ion concentration resulted in the predominance of Ni(NH3)n2+ or Ni(Ac)n(2−n) at the expense of Ni2+ and NiO, indicating a higher risk of nickel corrosion. Calculations showed that under normal operating conditions with [NH3]tot=5×10−5 and [CH3COO−]tot=10−8 m at 260 ℃ and 4.7 MPa, nickel will be passivated as NiO, preventing the rapid degradation of nickel-based alloys. However, in the presence of a crevice that allows the acetate ion to concentrate, nickel would dissolve in the form of the Ni2+ ion, endangering safe operation of CANDU SGs.

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Section: Resultssupporting

confidence: 82%

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Khollari¹,

Zebardast

Asselin

2023

Preprint

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Nickel‐based alloy corrosion in CANDU steam generators: E–pH diagrams of the Ni–NH₃–H₂O and Ni–CH₃COO⁻–H₂O ternary systems

Khollari,

Zebardast,

Asselin

2023

Materials & Corrosion

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Nuclear power plant steam generator (SG) tubes contain nickel as the main alloying element and there is concern about their corrosion. We optimized models for calculating the high‐temperature and high‐pressure thermodynamic properties of common nuclear alloy elements. Subsequently, we calculated the E–pH diagrams for nickel in different concentrations of ammonia or acetate ion at temperatures ranging from 100°C to 260°C and a pressure of 4.7 MPa. This information is used to predict the corrosion behavior of nickel in the secondary circuit conditions of Canadian Deuterium Uranium (CANDU) SGs. Increasing the ammonia or acetate ion concentration resulted in the predominance of Ni(NH3)n2+ or Ni(Ac)n(2−n) at the expense of Ni2+ and NiO, indicating a higher risk of nickel corrosion. Calculations showed that under normal operating conditions with [NH3]tot = 5 × 10−5 and [CH3COO−]tot = 10−8 m at 260°C and 4.7 MPa, nickel will be passivated as NiO, preventing the rapid degradation of nickel‐based alloys. However, in the presence of a crevice that allows the acetate ion to concentrate, nickel would dissolve in the form of the Ni2+ ion, endangering safe operation of CANDU SGs.

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The fretting tribocorrosion properties of CrAlTiN coating on the Inconel 690 alloy

Kang

Qiu

et al. 2023

J Mater Sci

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Corrosion of Alloy 690 in Simulated Steam Generator Crevices: Effect of Applied Potential, pH and Pb Addition

Cited by 8 publications

References 28 publications

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Nickel‐based alloy corrosion in CANDU steam generators: E–pH diagrams of the Ni–NH₃–H₂O and Ni–CH₃COO⁻–H₂O ternary systems

The fretting tribocorrosion properties of CrAlTiN coating on the Inconel 690 alloy

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Corrosion of Alloy 690 in Simulated Steam Generator Crevices: Effect of Applied Potential, pH and Pb Addition

Cited by 8 publications

References 28 publications

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Nickel-based alloy corrosion in CANDU steam generators: E-pH diagrams of the Ni-NH3-H2O and Ni-CH3COO−-H2O ternary systems

Nickel‐based alloy corrosion in CANDU steam generators: E–pH diagrams of the Ni–NH3–H2O and Ni–CH3COO−–H2O ternary systems

The fretting tribocorrosion properties of CrAlTiN coating on the Inconel 690 alloy

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Nickel‐based alloy corrosion in CANDU steam generators: E–pH diagrams of the Ni–NH₃–H₂O and Ni–CH₃COO⁻–H₂O ternary systems