Microstructural Evolution of Inconel 690 Alloy for Steam Generator Tubes

Inconel 690 alloy is a Ni-Cr-Fe austenite solid solution alloy with a wide range of applications such as steam generator tubes in nuclear power plant due to its good mechanical properties and corrosion resistance. In this study, the effects of heat treatment on the microstructural properties of Inconel 690 alloy were investigated. Inconel 690 alloy was annealed at solid solution temperature of 1150°C for 20 min, and cooled down to 800°C with different cooling rates, and then aged at 800°C for 100 min in vacuum, and then cooled down to room temperature by water quenching. The optical microscopy, scanning electron microscopy, and transmission electron microscopy results indicated that in case of the cooling rate of 0.5°C/min, discontinuous carbides along the grain boundaries were formed and when the cooling rate was 10°C/min, continuous carbides were formed. In both cases, many annealing twins were also formed. These results can help to improve the understanding of microstructural properties of Inconel 690 alloy.

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Parametric Study of External Pressure on Steam Generator Tube Bends

Volume 3: Design and Analysis ◽

10.1115/pvp2012-78592 ◽

2012 ◽

Author(s):

Mitch Hokazono ◽

Clayton T. Smith

Keyword(s):

Steam Generator ◽

Parametric Study ◽

External Pressure ◽

Light Water Reactor ◽

Material Strength ◽

Steam Generators ◽

Elliptical Cross ◽

Light Water ◽

Water Reactor ◽

Steam Generator Tubes

Integral light-water reactor designs propose the use of steam generators located within the reactor vessel. Steam generator tubes in these designs must withstand external pressure loadings to prevent buckling, which is affected by material strength, fabrication techniques, chemical environment and tube geometry. Experience with fired tube boilers has shown that buckling in boiler tubes is greatly alleviated by controlling ovality in bends when the tubes are fabricated. Light water reactor steam generator pressures will not cause a buckling problem in steam generators with reasonable fabrication limits on tube ovality and wall thinning. Utilizing existing Code rules, there is a significant design margin, even for the maximum differential pressure case. With reasonable bend design and fabrication limits the helical steam generator thermodynamic advantages can be realized without a buckling concern. This paper describes a theoretical methodology for determining allowable external pressure for steam generator tubes subject to tube ovality based on ASME Section III Code Case N-759-2 rules. A parametric study of the results of this methodology applied to an elliptical cross section with varying wall thicknesses, tube diameters, and ovality values is also presented.

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Behaviour of steam generator tubes in Belgium and its consequences

Nuclear Engineering and Design ◽

10.1016/0029-5493(92)90089-e ◽

1992 ◽

Vol 133 (1) ◽

pp. 63-69

Author(s):

G. Roussel ◽

P. Mignot

Keyword(s):

Steam Generator ◽

Steam Generator Tubes

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Evaluation of Motorized Rotating Pancake Coil Probe Signals Simulated by Numerical Analysis in Steam Generator Tubes

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.321-323.451 ◽

2006 ◽

Vol 321-323 ◽

pp. 451-454

Author(s):

Joo Young Yoo ◽

Sung Jin Song ◽

Chang Hwan Kim ◽

Hee Jun Jung ◽

Young Hwan Choi ◽

...

Keyword(s):

Numerical Simulation ◽

Numerical Analysis ◽

Steam Generator ◽

Integral Method ◽

Volume Integral ◽

Analysis Software ◽

Steam Generator Tubes ◽

Calibration Tool ◽

High Possibility ◽

Good Agreement

In the present study, the synthetic signals from the combo tube are simulated by using commercial electromagnetic numerical analysis software which has been developed based on a volume integral method. A comparison of the simulated signals to the experiments is made for the verification of accuracy, and then evaluation of five deliberated single circumferential indication signals is performed to explore a possibility of using a numerical simulation as a practical calibration tool. The good agreement between the evaluation results for two cases (calibration done by experiments and calibration made by simulation) demonstrates such a high possibility.

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Evaluation of the Creep Rupture Behavior of Alloy 690 Steam Generator Tubes Considering the Pressure Ramp Rate

Journal of Pressure Vessel Technology ◽

10.1115/1.4052450 ◽

2021 ◽

Author(s):

Jongmin Kim ◽

Min-Chul Kim ◽

Joonyeop Kwon

Keyword(s):

Steam Generator ◽

Creep Rupture ◽

Parameter Method ◽

Alloy 600 ◽

Steam Generator Tube ◽

Failure Pressure ◽

Alloy 690 ◽

Rupture Model ◽

Temperature And Pressure ◽

Steam Generator Tubes

Abstract The materials used previously for steam generator tubes around the world have been replaced and will be replaced by Alloy 690 given its improved corrosion resistance relative to that of Alloy 600. However, studies of the high- temperature creep and creep-rupture characteristics of steam generator tubes made of Alloy 690 are insufficient compared to those focusing on Alloy 600. In this study, several creep tests were conducted using half tube shape specimens of the Alloy 690 material at temperatures ranging from 650 to 850C and stresses in the range of 30 to 350 MPa, with failure times to creep rupture ranging from 3 to 870 hours. Based on the creep test results, creep life predictions were then made using the well-known Larson Miller Parameter method. Steam generator tube rupture tests were also conducted under the conditions of a constant temperature and pressure ramp using steam generator tube specimens. The rupture test equipment was designed and manufactured to simulate the transient state (rapid temperature and pressure changes) in the event of a severe accident condition. After the rupture test, the damage to the steam generator tubes was predicted using a creep rupture model and a flow stress model. A modified creep rupture model for Alloy 690 steam generator tube material is proposed based on the experimental results. A correction factor of 1.7 in the modified creep rupture model was derived for the Alloy 690 material. The predicted failure pressure was in good agreement with the experimental failure pressure.

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