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A System-Level Model for Estimating Residual Strain and Life of Nuclear Reactor Coolant System Components Under Connected-System-Thermal–Mechanical Boundary Conditions

  • Sp Iss: Advances in Residual Stress Technology
  • Published:
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Abstract

Background

Environmental-assisted fatigue (EAF) is a major issue for the long-term survival of nuclear power plant fleets in the U.S. and worldwide. Multi-material welded regions (e.g., nozzles) and other high-stress regions of reactor coolant system (RCS) components are prone to EAF-related damage.

Objective

The discussed work describes a system-level finite element (FE) model of RCS components of a pressurized water reactor (PWR). This is with the goal of predicting the stress hotspots, strain residuals, strain amplitudes and the resulting fatigue lives.

Methods

The FE model was developed considering system-level loading conditions (under connected system thermal–mechanical boundary conditions). Thermal–mechanical stress analysis was performed considering thermal stratification and a design-basis reactor loading cycle. Based on the FE model results, the strain residuals, strain amplitudes and resulting fatigue lives of RCS components were predicted.

Results

The results show that some of the RCS components can have significantly different strain amplitudes, residual strain, and fatigue lives, despite having similar geometry and material. Higher residual strain can lead to accelerated cyclic hardening of material and the associated effect of EAF. The simulated component-level strain profile (under realistic multi-axial-multi-physics loading cycle) can guide the selection of appropriate test inputs for conducting laboratory-scale EAF tests, which is a focus of future works.

Conclusions

Despite similar geometry and material the RCS component can have significantly different strain profiles and resulting fatigue lives. The discussed approach can help to identify and prioritize the RCS components for conducting expensive nondestructive evaluation (NDE) inspections.

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Abbreviations

CL:

Cold Leg

DMW:

Dissimilar Metal Weld

EAF:

Environmental Assisted Fatigue

HL:

Hot Leg

LAS:

Low Alloy Steel

LTO:

Long Term Operation

NDE:

Non-Destructive Evaluation

NPP:

Nuclear Power Plant

PRZ:

Pressurizer

PWR:

Pressurized Water Reactor

RCS:

Reactor Cooling System

RPV:

Reactor Pressure Vessel

SG:

Steam Generator

SL:

Surge Line

SMW:

Similar Metal Weld

SS:

Stainless Steel

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Acknowledgements and Funding

This research was supported through the U.S. Department of Energy’s Light Water Reactor Sustainability program under the work package of environmental fatigue study with program manager Dr. Thomas. M. Rosseel and deputy program manager Dr. Xiang (Frank) Chen.

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Correspondence to S. Mohanty.

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The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

Appendix

Appendix

Expansion coefficients for 316SS and 508LAS base, 316SS-316SS SW filler, and 316SS-508LAS DW filler and butter welds.

Temp (°C)

316SS base metals

508LAS base metals

316SS-316SS SW filler (E316-16) welds

316SS-508LAS DW filler (In 82) welds

316SS-508LAS DW butter (In 182) welds

Expansion coeff (1/°C)

Expansion coeff (1/°C)

Expansion coeff (1/°C)

Expansion coeff (1/ °C)

Expansion coeff (1/ °C)

21.11

2.8385E-06

8.0805e-06

4.4273e-07

3.3078e-06

7.9477e-06

31.11

2.8385E-06

8.2561e-06

4.4273e-07

4.067e-06

7.8772e-06

41.11

3.4739E-06

8.7299e-06

8.7463e-07

4.7487e-06

7.8772e-06

51.11

4.6378E-06

9.1746e-06

2.2e-06

5.2931e-06

7.8772e-06

61.11

5.7242E-06

9.5914e-06

3.4306e-06

5.7206e-06

7.8772e-06

71.11

6.7361E-06

9.9815e-06

4.5703e-06

6.0495e-06

8.8574e-06

81.11

7.6763E-06

1.0346e-05

5.6232e-06

6.2969e-06

9.9318e-06

91.11

8.5479E-06

1.0686e-05

6.5934e-06

6.4781e-06

1.0949e-05

101.11

9.3536E-06

1.1003e-05

7.4849e-06

6.6072e-06

1.1855e-05

111.11

1.0096E-05

1.1298e-05

8.3017e-06

6.6965e-06

1.2624e-05

121.11

1.0779E-05

1.1572e-05

9.0479e-06

6.7574e-06

1.3251e-05

131.11

1.1405E-05

1.1826e-05

9.7275e-06

6.7998e-06

1.375e-05

141.11

1.1976E-05

1.2062e-05

1.0344e-05

6.8322e-06

1.414e-05

151.11

1.2496E-05

1.2281e-05

1.0903e-05

6.8621e-06

1.4445e-05

161.11

1.2967E-05

1.2483e-05

1.1407e-05

6.896e-06

1.4693e-05

171.11

1.3393E-05

1.267e-05

1.186e-05

6.9392e-06

1.4906e-05

181.11

1.3776E-05

1.2843e-05

1.2267e-05

6.9961e-06

1.5104e-05

191.11

1.4119E-05

1.3004e-05

1.2632e-05

7.0699e-06

1.5301e-05

201.11

1.4425E-05

1.3153e-05

1.2958e-05

7.1633e-06

1.5506e-05

211.11

1.4697E-05

1.3292e-05

1.325e-05

7.278e-06

1.572e-05

221.11

1.4938E-05

1.3422e-05

1.3512e-05

7.415e-06

1.5941e-05

231.11

1.5151E-05

1.3544e-05

1.3747e-05

7.5745e-06

1.6162e-05

241.11

1.5338E-05

1.3659e-05

1.396e-05

7.7563e-06

1.6372e-05

251.11

1.5503E-05

1.3768e-05

1.4155e-05

7.9594e-06

1.6558e-05

261.11

1.5648E-05

1.3873e-05

1.4336e-05

8.1823e-06

1.6709e-05

271.11

1.5777E-05

1.3974e-05

1.4506e-05

8.4232e-06

1.6816e-05

281.11

1.5891E-05

1.4073e-05

1.4671e-05

8.6799e-06

1.6872e-05

291.11

1.5995E-05

1.4172e-05

1.4833e-05

8.9497e-06

1.6878e-05

301.11

1.6091E-05

1.427e-05

1.4998e-05

9.2298e-06

1.6842e-05

311.11

1.6181E-05

1.437e-05

1.5168e-05

9.5171e-06

1.6783e-05

321.11

1.6269E-05

1.4473e-05

1.5348e-05

9.8083e-06

1.6728e-05

331.11

1.6358E-05

1.4579e-05

1.5543e-05

1.01e-05

1.672e-05

341.11

1.6450E-05

1.469e-05

1.5755e-05

1.0389e-05

1.6811e-05

350

1.6538E-05

1.4794e-05

1.5963e-05

1.0642e-05

1.7028e-05

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Mohanty, S. A System-Level Model for Estimating Residual Strain and Life of Nuclear Reactor Coolant System Components Under Connected-System-Thermal–Mechanical Boundary Conditions. Exp Mech 62, 1501–1517 (2022). https://doi.org/10.1007/s11340-022-00847-5

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