<b><i>2000 F.N. Speller Award Lecture:</i></b>Stress Corrosion Cracking in Pressurized Water Reactors—Interpretation, Modeling, and Remedies

Scott, Peter

doi:10.5006/1.3280580

Cited by 88 publications

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“…Stress corrosion crack (SCC) initiation and growth experiments on nickel-based alloys has been conducted by many researchers to characterize cracking in pressurized water reactor (PWR) primary water conditions. [1][2][3][4][5] Testing conducted by varying the dissolved hydrogen concentration has shown that nickel-based alloys have a maximum in the cracking susceptibility near the Ni/NiO phase transition.…”

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Determination of the Nickel/Nickel Oxide Phase Transition and Henry's Constant in Hydrogenated Subcritical and Supercritical Water

Moss

Was

2014

J. Electrochem. Soc.

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The objective of this study is to determine the temperature dependence of the nickel/nickel oxide phase transition using additions of dissolved hydrogen in subcritical and supercritical water. The dissolved hydrogen at the Ni/NiO boundary was measured by direct exposure of nickel coupons at 320 to 450 • C and 25 MPa. The stable form of nickel at each exposure condition was determined by optical examination and confirmed by nuclear reaction analysis. Henry's law constant as a function of temperature was determined in-situ by measuring the fugacity of hydrogen through a palladium-silver tube using known dissolved hydrogen concentrations. Below 320 • C, Henry's constant decreases linearly up to the critical temperature, above which the slope becomes temperature independent. The effect of water density on Henry's law constant was determined. A thermodynamic model for hydrogen fugacity at the Ni/NiO phase boundary was developed and was shown to agree with the measured data. The deviation in the fugacity at the critical temperature was accounted for by the inclusion of activity of water in the model, highlighting the importance of thermodynamic properties of solvents in high temperature oxidation. Stress corrosion crack (SCC) initiation and growth experiments on nickel-based alloys has been conducted by many researchers to characterize cracking in pressurized water reactor (PWR) primary water conditions. [1][2][3][4][5] Testing conducted by varying the dissolved hydrogen concentration has shown that nickel-based alloys have a maximum in the cracking susceptibility near the Ni/NiO phase transition.6-8 Both exposure data and calculations show that the dissolved hydrogen concentration required to stabilize nickel increases with temperature. 9Given the importance of the Ni/NiO transition in SCC, accelerated testing at higher temperatures than in service should then account for this shift in the transition with temperature. Increasing the testing temperature beyond PWR conditions (∼320• C) is appealing for accelerated experiments, but the extent to which this can be done is limited, given the transition to the supercritical water phase (SCW) at 374• C. Testing in this temperature range is also appealing for addressing supercritical water reactor conditions which operate at water temperatures up to 625• C at 25 MPa. 10 However, the location of the Ni/NiO boundary in water is not known at temperatures higher than the typical accelerated testing temperature of 360• C. Extensive experiments on the stability of nickel in water as a function of dissolved hydrogen concentration have been conducted by Attansio and Morton 9 by contact electrode resistance measurements of oxide films up to 360• C. Further work was conducted to determine thermodynamics of nickel oxidation by measuring the fugacity of hydrogen using a palladium-silver thimble and estimations of the Henry's law constant from unpublished data of Moshier and Witt. 11However, Attanasio and Morton 8 found that the measured standard state entropy and enthalpy disagree sligh...

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“…[1][2][3][4][5] Testing conducted by varying the dissolved hydrogen concentration has shown that nickel-based alloys have a maximum in the cracking susceptibility near the Ni/NiO phase transition. [6][7][8] Both exposure data and calculations show that the dissolved hydrogen concentration required to stabilize nickel increases with temperature.…”

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confidence: 99%

Determination of the Nickel/Nickel Oxide Phase Transition and Henry's Constant in Hydrogenated Subcritical and Supercritical Water

Moss

Was

2014

J. Electrochem. Soc.

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“…The intergranular stress corrosion cracking rate varies significantly depending on the test conditions, microstructure of the components, and so on. A great deal of research on stress corrosion cracking in primary water reactor environments has been carried out to demonstrate the cracking mechanism models [3,4] in which oxide films at grain boundaries results in the intergranular stress corrosion cracking and effects of various factors on the crack growth rate [5,6]. Recently, it has been reported that the intergranular stress corrosion cracking was observed in low carbon decarburized steels [7].…”

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Primary water stress corrosion cracking in alloy 600 and intergranular crack growth rate

et al. 2010

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The effects of the stress intensity factor and dissolved hydrogen on the crack growth rate in primary water reactor environments was investigated with alloy 600 with continuous carbide films at grain boundaries. A primary water stress corrosion cracking of intergranular fracture mode was observed. The intergranular crack growth rate decreased with a decreasing stress intensity factor, and the dissolved hydrogen content influenced the crack growth rate. Such results are consistent with those reported previously.

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“…[1,2], which creates a safety problem by leaking radioactive primary cooling water and a huge economical loss due to unexpected trips of the operating plant resulting in a reduction in its operation efficiency and additional maintenance costs. Nowadays, in particular, stress corrosion cracking (SCC), both of outer diameter stress corrosion cracking (ODSCC or IGSCC) and primary water stress corrosion cracking (PWSCC) occurring on the expansion transition regions of the tubes is a main issue concerning steam generators in pressurized water reactor (PWR) nuclear power plants [3,4]. At present, the tubes damaged by SCC during operations are plugged with plugs made of Alloy 690 or sleeved with sleeve tubes with a smaller diameter than the mother tubes by inserting them into the damaged tubes, followed by welding the sleeve tubes to the mother ones or explosively expanding both ends of the sleeved tubes.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of electrodeposited ternary Ni-alloys for thermal stability

Kim

et al. 2011

Met. Mater. Int.

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Electroplating methods for ternary Ni-alloys, such as Ni-P-Fe and Ni-P-B, in a Ni sulfamate solution on the inner wall surfaces of Alloy 600 tubing have been developed in order to use them to repair steam generator tubes damaged by a variety of corrosion mechanisms, in particular, by stress corrosion cracking. In this study, the stability of their microstructures and mechanical properties were evaluated to check if they could be used for a long period of time at the operating temperature of a PWR (pressurized water reactor) in nuclear power plants. The specimens were heat treated at 325°C and 400°C for 10, 20 and 30 days, followed by observation of their microstructures and measurement of their microhardness and tensile property. According to the experiment results, there was no noticeable change in their microstructures or microhardness with the heat treatment temperature and time conditions used in this study. For a Ni-P-B deposit, the ultimate tensile strength (UTS) slightly increased with the heat treatment time, while their elongation decreased. In the case of a Ni-P-Fe deposit, however, its tensile property varied with the applied current density. For a Ni-P-Fe deposit plated at an applied current density of 50 mA/cm 2 , its UTS slightly decreased, but its elongation slightly increased with the heat treatment time. We concluded that the thermal stability of the ternary Ni-alloy deposits used in this study is good enough to be used with the materials of operating nuclear power plants.

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2000 F.N. Speller Award Lecture:Stress Corrosion Cracking in Pressurized Water Reactors—Interpretation, Modeling, and Remedies

Cited by 88 publications

References 0 publications

Determination of the Nickel/Nickel Oxide Phase Transition and Henry's Constant in Hydrogenated Subcritical and Supercritical Water

Determination of the Nickel/Nickel Oxide Phase Transition and Henry's Constant in Hydrogenated Subcritical and Supercritical Water

Primary water stress corrosion cracking in alloy 600 and intergranular crack growth rate

Evaluation of electrodeposited ternary Ni-alloys for thermal stability

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