The RSE-M Code provides rules and requirements for inservice inspection of French Pressurized Water Reactor power plant components. Appendices 5.3 and 5.4 of the Code give non mandatory guidance for analytical evaluation of flaws, i.e. fracture mechanics analyses based on simplified methods. Flaw assessment aims to calculate the initiation and the subsequent propagation of the crack under cyclic loading (fatigue analysis) and then to assess the crack stability, by comparing the applied J integral to the toughness of the material. This paper shows an overview of the R&D work undergone to make possible an analytical approach: • analytical formulas for the elastic stress field in elbows under in-plane, out-of-plane and torsion moments, • stress intensity factors solutions based on the influence coefficient method for surface and embedded cracks in pipes, • simplified methods to estimate the J integral for various configurations of piping, flaws and loading. These methods are shortly presented, including their field of application and their validation.

This paper discusses cyclic deformation and fatigue behavior of three grades of stainless steel 304L. Effects of pre-straining and mean stress were investigated and it was observed that these parameters influence both deformation and fatigue behaviors. At HCF, significant secondary hardening was observed for two of the materials, leading to a significant change in fatigue behavior at long lives. For two of the materials, pre-strained tests were also conducted. Hardening was observed as a consequence of pre-straining and affected further deformation and fatigue behaviors significantly. Mean stress effects on fatigue lives were as expected, as compressive mean stress lengthened life and tensile mean stress shortened life. The Smith-Watson-Topper (SWT) parameter was used to correlate the experimental data from all test conditions for the three materials and was found to correlate the experimental data reasonably well.

On the idea that fatigue damage is localized at the microscopic scale, a scale smaller than the mesoscopic one of the Representative Volume Element (RVE), a three-dimensional two scale damage model has been proposed in the past decade at LMT-Cachan for High Cycle Fatigue applications. It consists in the micromechanics analysis of a weak micro-inclusion subjected to plasticity and damage embedded in an elastic meso-element (the RVE of continuum mechanics). The consideration of plasticity coupled with damage equations at microscale, altogether with Eshelby-Kro¨ner localization law, allows to compute the value of microscopic damage up to failure for any kind of loading, 1D or 3D, cyclic or random, isothermal or anisothermal, mechanical, thermal or thermomechanical. A robust numerical scheme makes the computations fast and the new programming of a graphical user interface gives a software simple to use with facilities for material parameters identification: DAMAGE-2005. Examples of thermal and thermomechanical fatigue as well as applications on E.D.F. FATHER and INTHERPOL structures subjected to complex thermo-mechanical fatigue are detailed.

The RSE-M Code provides rules and requirements for in-service inspection of French Pressurized Water Reactor power plant components. The Code gives non mandatory guidance for analytical evaluation of flaws. To calculate the stress intensity factors in pipes and shells containing semi-elliptical surface defects, influence coefficients are given for a wide range of geometrical parameters. To calculate the J integral for a circumferential surface crack in a straight pipe, simplified methods are available in the present version of the Code (2000 Addenda) for mechanical loads (in-plane bending and torsion moments, pressure), thermal loads as well as for the combination of these loads. This paper presents the recent advances in the development of J-estimation schemes for two configurations: • a longitudinal surface crack in a straight pipe, • a longitudinal surface crack in the mid-section of an elbow.

The RSE-M Code [1] provides rules and requirements for in-service inspection of French Pressurized Water Reactor power plant components. Non mandatory guidance is given in the Code for analytical flaw evaluation in a wide range of situations. In Appendix 5.4 of the Code, influence coefficients are provided to calculate stress intensity factors in pipes and shells containing semi-elliptical surface defects. The J assessment method is based on the reference stress concept with two options for reference loads evaluation: “CEP elastic plastic stress” and “CLC modified limit load”. In this paper recent advances concerning J assessment under mechanical loading for a crack located in a pipe-elbow junction are presented. Reference stress evaluation with “CLC” option is developed and mechanical foundations of the equation of large scale yielding under complex loading (pressure, in-plane and out-of-plane bending) are presented.