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HomeAssessment of thermal fatigue crack growth in the high cycle domain under sinusoidal thermal loading an application
Civaux 1 case
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The assessment of fatigue crack growth due to cyclic thermal loads arising from turbulent mixing presents significant challenges, principally due to the difficulty of establishing the actual loading spectrum. So-called sinusoidal methods represents a simplified approach in which the entire spectrum is replaced by a sine-wave variation of the temperature at the inner pipe surface. The amplitude can be conservatively estimated from the nominal temperature difference between the two flows which are mixing; however a critical frequency value must be determined numerically so as to achieve a minimum predicted life. The need for multiple calculations in this process has lead to the development of analytical solutions for thermal stresses in a pipe subject to sinusoidal thermal loading, described in a companion report. Based on these stress distributions solutions, the present report presents a methodology for assessment of thermal fatigue crack growth life. The critical sine wave frequency is calculated for both axial and hoop stress components as the value that produces the maximum tensile stress component at the inner surface. Using these through-wall stress distributions, the corresponding stress intensity factors for a long axial crack and a fully circumferential crack are calculated for a range of crack depths using handbook K solutions. By substituting these in a Paris law and integrating, a conservative estimate of thermal fatigue crack growth life is obtained. The application of the method is described for the pipe geometry and loadings conditions reported for the Civaux 1 case. Additionally, finite element analyses were used to check the thermal stress profiles and the stress intensity factors derived from the analytical model. The resulting predictions of crack growth life are comparable with those reported in the literature from more detailed analyses and are lower bound, as would be expected given the conservative assumptions made in the model.
- Published:
- Corporate author(s): Institute for Energy and Transport (Joint Research Centre)
- Personal author(s): Radu, V ; Taylor, N ; Paffumi, E
- Themes: Nuclear energy and safety , Energy research
- Subject: France , nuclear power station , nuclear research , nuclear safety , nuclear technology , reactor cooling system
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| ISSN 1018-5593 | ISBN 978-92-79-08218-4 | DOI 10.2790/4943 | Catalogue number LD-NA-23223-EN-C |
- Released on EU publications website:
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