scholarly journals Inclusion of Warm Pre-Stress Concept in French RPV Structural Integrity Assessment

2016 ◽  
Author(s):  
Dominique Moinereau ◽  
Malik Ait-Bachir ◽  
Stéphane Chapuliot ◽  
Stéphane Marie ◽  
Clémentine Jacquemoud ◽  
...  
Keyword(s):  
Brittle Fracture ◽  
Fracture Resistance ◽  
Large Scale ◽  
Structural Integrity ◽  
Stress Effect ◽  
Local Approach ◽  
Experimental Database ◽  
Term Operation ◽  
Integrity Assessment ◽  
Brittle Fracture Resistance

Evaluation of the fracture resistance of nuclear reactor pressure vessel (RPV) regarding the risk of brittle fracture is a key point in the structural integrity assessment of the component (RPV). Such approach is codified in French RSE-M code, based on a very conservative methodology. With respect to long term operation, an improvement of the present methodology is necessary and in progress to reduce this conservatism. One possible significant improvement is the inclusion of the warm pre-stress (WPS) concept in the assessment. After a short description of the WPS concept, the process engaged in France to allow inclusion of WPS in the integrity assessment is presented. In a first step, experimental and numerical studies have been conducted in France by EDF, CEA and AREVA (also including international collaborations and projects) to demonstrate and validate the beneficial effect of WPS on the brittle fracture resistance of RPV steels. A large panel of experimental results and data is now available obtained on small, medium and large scale specimens on representative RPV steels (including highly irradiated RPV materials). These data have been included in a specific WPS experimental database. Main experiments have been interpreted by refined computations, based on elastic plastic analyses and local approach to cleavage fracture. In a second step, a new criterion (ACE criterion) has been proposed by French organizations (AREVA, CEA and EDF) for an easy simplified evaluation of warm pre-stress effect on the brittle fracture resistance of RPV steels. Accuracy and conservatism of the criterion is verified by comparison to experimental data results and numerical analyses. Finally, implementation of the WPS effect in the French RSE-M code (for in service assessment) is in progress, based on the ACE criterion. The present paper summarizes all these steps leading to codification of WPS in RSE-M code.

Advanced Structural Integrity Assessment Tools for Safe Long Term Operation: ATLAS+ Project — Status of the Activities of the WP3 on Modelling

2019 ◽  
Author(s):  
Stéphane Marie ◽  
Arnaud Blouin ◽  
Tomas Nicak ◽  
Dominique Moinereau ◽  
Anna Dahl ◽  
...  
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Local Approach ◽  
Coupled Models ◽  
Large Defect ◽  
Ductile Tearing ◽  
Term Operation ◽  
Integrity Assessment

Abstract The main objective and mission of the ATLAS+ project is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. ATLAS+ WP3 focuses mainly on ductile tearing prediction for large defect in components: Several approaches have been developed to accurately model the ductile tearing process and to take into account phenomena such as the triaxiality effect, or the ability to predict large tearing in industrial components. These advanced models include local approach coupled models or advanced energetic approaches. Unfortunately, the application of these tools is today rather limited to R&D expertise. However, because of the continuous progress in the performance of the calculation tools and accumulated knowledge, in particular by members of ATLAS+, these models can now be considered as relevant for application in the context of engineering assessments. WP3 will therefore: • Illustrate the implementation of these models for industrial applications through the interpretation of large scale mock-ups (with cracks in weld joints for some of them), • Make recommendations for the implementation of the advanced models in engineering assessments, • Correct data from the conventional engineering approach by developing a methodology to produce J-Δa curve suitable case by case, based on local approach models, • Improve the tools, guidance and procedures for undertaking leak-before-break (LBB) assessments of piping components, particularly in relation to representing structural representative fracture toughness J-Resistance curves and the influence of weld residual stresses. To achieve these goals, WP3 is divided into 4 sub-WPs and this paper presents the progress of the work performed in each sub-WP after 24 months of activities.

Advanced Structural Integrity Assessment Tools for Safe Long Term Operation: ATLAS+ Project — Status of the Activities of the WP3 on Modelling in 2020

2020 ◽  
Author(s):  
Arnaud Blouin ◽  
Stéphane Marie ◽  
Tomas Nicak ◽  
Antti Timperi ◽  
Peter Gill
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Local Approach ◽  
Coupled Models ◽  
Large Defect ◽  
Ductile Tearing ◽  
Term Operation ◽  
Integrity Assessment

Abstract The main objective and mission of the ATLAS+ project is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. ATLAS+ WP3 focuses mainly on ductile tearing prediction for large defect in piping and associated components: Several approaches have been developed to accurately model the ductile tearing process and to take into account phenomena such as triaxiality effects, or the ability to predict large tearing in industrial components. These advanced models include local approach coupled models or advanced energetic approaches. Unfortunately, the application of these tools is currently rather limited to R&D expertise. However, because of the continuous progress in the performance of calculation tools and accumulated knowledge, in particular by members of the ATLAS+ consortium, these models can now be considered as relevant for application in the context of engineering assessments. WP3 has been planned to: • Illustrate the implementation of these models for industrial applications through the interpretation of large scale mock-ups (with cracks in weld joints for some of them), • Make recommendations for the implementation of the advanced models in engineering assessments, • Correct data from the conventional engineering approach by developing a methodology to produce J-Δa curve suitable case by case, based on local approach models, • Improve the tools, guidance and procedures for undertaking leak-before-break (LBB) assessments of piping components, particularly in relation to representing structural representative fracture toughness J-Resistance curves and the influence of weld residual stresses. To achieve these goals, WP3 is divided into 4 sub-WPs and this paper presents the progress of the work performed in each sub-WP after 36 months of activities.

Validation of ACE Analytical Criterion for Warm Pre-Stress Evaluation in RPV Integrity Assessment

2015 ◽  
Author(s):  
Dominique Moinereau ◽  
Caroline Landron ◽  
Stéphane Chapuliot ◽  
Stéphane Marie
Keyword(s):  
Fracture Resistance ◽  
Large Scale ◽  
Stress Effect ◽  
Stress Evaluation ◽  
Experimental Database ◽  
Integrity Assessment ◽  
Numerical Studies ◽  
Large Panel ◽  
Analytical Criterion ◽  
Reactor Pressure

Numerous experimental and numerical studies have been conducted in France to demonstrate the beneficial effect of warm pre-stress (WPS) on the brittle fracture resistance of reactor pressure vessel (RPV) steels and take into account this effect in French RPV integrity assessment. A large panel of experimental data is available, obtained on small, medium and large scale specimens. These data have been included in a specific EDF WPS experimental database. An analytical criterion — ACE criterion — is proposed by French organizations (AREVA, CEA and EDF) for analytical evaluation of warm pre-stress effect on the brittle resistance of RPV steels. After a description of ACE criterion and the EDF WPS database, the validation of the criterion is shown — based on this database — by comparison between experimental results and predictions of the model.

The Experimental Work in Support to ATLAS+ Project

2018 ◽  
Author(s):  
Dominique Moinereau ◽  
Patrick Le Delliou ◽  
Anna Dahl ◽  
Yann Kayser ◽  
Szabolcs Szavai ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Experimental Work ◽  
Large Scale ◽  
Nuclear Reactor ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Ductile Material ◽  
Small Scale ◽  
Term Operation ◽  
Integrity Assessment

The 4-years European project ATLAS+ project was launched in June 2017. Its main objective is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. The transferability of ductile material properties from small scale fracture mechanics specimens to large scale components is one of the topics of the project. A large programme of experimental work is to be conducted in support of the development and validation of advanced tools for structural integrity assessment within the framework of the work-package 1 (WP 1): Design and execution of simulation oriented experiments to validate models at different scales. The experimental work is based on a full set of fracture mechanics experiments conducted on standard specimens and large scale components (several pipes and one mock-up), including a full materials characterization. Three materials are considered: • a ferritic steel 15NiCuMoNb5 (WB 36) • an aged austenitic stainless steel weld • a VVER (eastern PWR) dissimilar metal weld (DMW) The paper presents the WP 1, the experimental programme and summarizes the first results.

Loading mode effect on brittle fracture resistance of cracked component under large-scale yielding

2021 ◽  
pp. 104115
Author(s):  
Kazuma Shimizu ◽  
Mitsuru Ohata ◽  
Hiroto Shoji ◽  
Hiroyasu Tanigawa ◽  
Taichiro Kato
Keyword(s):  
Brittle Fracture ◽  
Fracture Resistance ◽  
Large Scale ◽  
Loading Mode ◽  
Brittle Fracture Resistance ◽  
Mode Effect ◽  
Scale Yielding

Project STYLE: Post-Test Analysis of Mock-Up3

2014 ◽  
Author(s):  
Tomas Nicak ◽  
Herbert Schendzielorz ◽  
Elisabeth Keim ◽  
Gottfried Meier ◽  
Dominique Moinereau ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Large Scale ◽  
Structural Integrity ◽  
Small Scale ◽  
Primary Circuit ◽  
Term Operation ◽  
Integrity Assessment ◽  
Work Related ◽  
Post Test ◽  
Circuit Components

The safety and reliability of all systems has to be maintained throughout the lifetime of a nuclear power plant. Continuous R&D work is needed in targeted areas to meet the challenges of long term operation of existing and new plants designs. The European project STYLE aims to develop and validate advanced methods of structural integrity assessment applicable in the ageing and lifetime management of primary circuit components. There are three large scale mock-up tests in STYLE each of them dedicated to investigate specific effects. This paper presents the work related to Mock-up3, which is dedicated to investigate influence of cladding on the crack initiation and propagation as well as the transferability of material properties from small scale specimens to a large scale component. The performed post-test analyses focus on both the further understanding and interpretation of the Mock-up3 test and on the effect of cladding on structural integrity and LBB behavior of reactor coolant pressure boundary components.

Elastic-Plastic Fracture Mechanics Analysis of Cast Stainless Steel Pipes (Influence of Axial Load on Z-Factor of Pipes With Circumferential Crack Under Bending Load)

2013 ◽  
Author(s):  
Masayuki Kamaya ◽  
Kiminobu Hojo
Keyword(s):  
Stainless Steel ◽  
Axial Load ◽  
Power Plants ◽  
Structural Integrity ◽  
Term Operation ◽  
Steel Pipes ◽  
Integrity Assessment ◽  
Plastic Failure ◽  
Elastic Plastic ◽  
Bending Load

Since the ductility of cast austenitic stainless steel pipes decreases due to thermal aging embrittlement after long term operation, not only plastic collapse failure but also unstable ductile crack propagation (elastic-plastic failure) should be taken into account for the structural integrity assessment of cracked pipes. In the ASME Section XI, the load multiplier (Z-factor) is used to derive the elastic-plastic failure of the cracked components. The Z-factor of cracked pipes under bending load has been obtained without considering the axial load. In this study, the influence of the axial load on Z-factor was quantified through elastic-plastic failure analyses under various conditions. It was concluded that the axial load increased the Z-factor; however, the magnitude of the increase was not significant, particularly for the main coolant pipes of PWR nuclear power plants.

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