INCEFA-PLUS (Increasing Safety in Nuclear Power Plants by Covering Gaps in Environmental Fatigue Assessment)

INCEFA-PLUS is a major new five year project supported by the European Commission HORIZON2020 program. The project commenced in mid 2015. 16 organizations from across Europe have combined forces to deliver new experimental data which will support the development of improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Prior to the start of INCEFA-PLUS, an in-kind study was undertaken by several European organizations with the aim of developing the current state of the art for this technical area. In addition to stress/strain amplitude, this study identified three additional experimental variables which required further study in order to support improved assessment methodology for environmental fatigue, namely the effects of mean stress/strain, hold time and surface finish. Within INCEFA-PLUS, the effects of these three variables on fatigue endurance of austenitic stainless steels in light water reactor environments are therefore being studied experimentally. The data obtained will be collected and standardized in an online environmental fatigue database. A dedicated CEN workshop will deliver a harmonized data format facilitating the exchange of data within the project but also beyond. Based on the data generated and the resulting improvement in understanding, it is planned that INCEFA-PLUS will develop and disseminate methods for including the new data into assessment procedures for environmental fatigue degradation. This will take better account of the effects of mean stress/strain, hold time and surface finish. This paper will describe the background to the project and will explain the expectations for it.

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INCEFA-PLUS (Increasing Safety in Nuclear Power Plants by Covering Gaps in Environmental Fatigue Assessment)

Volume 1A: Codes and Standards ◽

10.1115/pvp2017-65256 ◽

2017 ◽

Cited By ~ 1

Author(s):

Kevin Mottershead ◽

Matthias Bruchhausen ◽

Thomas Métais ◽

Sergio Cicero ◽

David Tice

Keyword(s):

Test Data ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Phase 1 ◽

Hold Time ◽

Austenitic Stainless Steels ◽

Common Interest ◽

Mean Stress ◽

Surface Finishes

INCEFA-PLUS is a five year project supported by the European Commission HORIZON2020 program. The project commenced in mid-2015. 16 organizations from across Europe have combined forces to deliver new experimental data which will support the development of improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Within INCEFA-PLUS, the effects of mean strain, hold time, strain amplitude and surface finish on fatigue endurance of austenitic stainless steels in light water reactor environments are being studied experimentally, these being issues of common interest to all participants. The data obtained are being collected and standardized in an online environmental fatigue database, implemented with the assistance of a CEN workshop led by members of the INCEFA-PLUS project. Later in the project it is planned that INCEFA-PLUS will develop and disseminate methods for including the new data into assessment approaches for environmental fatigue degradation. This paper provides an update to the project introduction presented at PVP2016 (PVP2016-63149). In particular the paper presents the finalized matrix of test conditions for Phase 1 testing planned for 2017, including the agreed positions on testing for the effects of mean stress/strain and hold time. The materials being tested are summarized, together with available material characterization data. The specimen surface finishes used in the phase 1 testing are described, including measures taken to ensure uniformity of surface conditions throughout the consortium and characterization results for the two chosen surface finishes for each specimen geometry and material. The emerging plans for Phase 2 testing is also described, with a focus on steps being taken to enable more plant-relevant testing for the effects of mean stress and exploration of sensitivities to hold times within plant transients. The latest view on how the project results will be used to advance development of improved assessment guidelines is also discussed. An update is provided on the discussions at the CEN workshop on Standards-Compliant Formats for Fatigue Test Data (FATEDA) including progress towards agreeing test data formats and trials of XML data transfers from laboratory to database. Finally, a summary is provided of project dissemination activities.

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INCEFA-PLUS: Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment

Volume 1: Codes and Standards ◽

10.1115/pvp2020-21220 ◽

2020 ◽

Author(s):

Kevin Mottershead ◽

Matthias Bruchhausen ◽

Sergio Cicero ◽

Sam Cuvilliez

Keyword(s):

Strain Amplitude ◽

Surface Finish ◽

Nuclear Power ◽

Power Plants ◽

Hold Time ◽

Austenitic Stainless Steels ◽

Common Interest ◽

The Status ◽

Assessment Guidelines ◽

Mean Strain

Abstract INCEFA-PLUS is a five year project supported by the European Commission HORIZON2020 programme. The project concludes in June 2020. 16 organisations from across Europe have combined forces to deliver new experimental data which is being used to develop improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Within INCEFA-PLUS, the effects of mean strain and stress, hold time, strain amplitude and surface finish on fatigue endurance of austenitic stainless steels in light water reactor environments have been studied experimentally, these being issues of common interest to all participants. The data obtained has been collected and standardised in an online environmental fatigue database, implemented with the assistance of an INCEFA-PLUS led CEN workshop on this aspect. As the end of the project approaches, INCEFA-PLUS is developing and disseminating methods for including the new data into assessment approaches for environmental fatigue degradation. This paper provides an overall update to project developments since it was last presented at PVP2019 (PVP2019-93276), and provides provisional project conclusions (which will be finalised for presentation at the conference). As well as being a standalone paper, the paper will also serve as an introduction to other papers being submitted covering specific aspects of the project. In particular this paper summarises: • The results of 3 years of testing (nearly concluded at the time of paper submission) • A summary of revealed sensitivities to, and inter-dependencies between: ○ Mean strain and stress, surface finish, strain amplitude and hold time. ○ Environment ○ Material ○ Laboratory (including specimen size and form) • The latest thoughts on how the project results will be used to advance development of improved assessment guidelines. • Progress developing an International EAF database. • A summary of dissemination achieved and planned. • The status of INCEFA-SCALE plans for work after the end of INCEFA-PLUS.

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INCEFA-PLUS: Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment

Volume 1A: Codes and Standards ◽

10.1115/pvp2018-84034 ◽

2018 ◽

Cited By ~ 1

Author(s):

Kevin Mottershead ◽

Matthias Bruchhausen ◽

Sam Cuvilliez ◽

Sergio Cicero

Keyword(s):

Strain Amplitude ◽

Surface Finish ◽

Nuclear Power ◽

Power Plants ◽

Phase 1 ◽

Hold Time ◽

Austenitic Stainless Steels ◽

Common Interest ◽

Horizon 2020 ◽

Mean Strain

INCEFA-PLUS is a five-year project supported by the European Commission HORIZON 2020 programme. The project commenced in mid-2015. Sixteen organisations from across Europe have combined forces to deliver new experimental data which will support the development of improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Within INCEFA-PLUS, the effects of mean strain and stress, hold time, strain amplitude and surface finish on fatigue endurance of austenitic stainless steels in light water reactor environments are being studied experimentally, these being issues of common interest to all participants. The data obtained is being collected and standardised in an online environmental fatigue database, implemented with the assistance of an INCEFA-PLUS led CEN (European Committee for Standardization) workshop on this aspect. Later in the project it is planned that INCEFA-PLUS will develop and disseminate methods for including the new data into assessment approaches for environmental fatigue degradation. This paper provides an overall update to project developments since it was last presented at PVP2017 [[1]]. As well as being a standalone paper, the paper will also serve as an introduction to more detailed papers also being submitted covering 4 specific aspects of the project. In particular, this paper summarises: • The results for Phase 1 testing. • The agreed plans for Phase 2 testing • A summary of emerging sensitivities to, and inter-dependencies between: ○ Mean strain and stress, surface finish, strain amplitude and hold time. ○ Environment ○ Material ○ Laboratory • Latest thinking on direction for the project in its last two years. • The latest thoughts on how the project results will be used to advance development of improved assessment guidelines. • A summary of dissemination achieved and planned for the forthcoming year.

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INCEFA-PLUS: Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment

Volume 1: Codes and Standards ◽

10.1115/pvp2019-93276 ◽

2019 ◽

Author(s):

Kevin Mottershead ◽

Matthias Bruchhausen ◽

Sergio Cicero ◽

Sam Cuvilliez

Keyword(s):

Strain Amplitude ◽

Surface Finish ◽

Nuclear Power ◽

Power Plants ◽

Hold Time ◽

Austenitic Stainless Steels ◽

Companion Paper ◽

Common Interest ◽

Assessment Guidelines ◽

Mean Strain

Abstract INCEFA-PLUS is a five year project supported by the European Commission HORIZON2020 programme. The project commenced in mid-2015. Sixteen organisations from across Europe have combined forces to deliver new experimental data which will support the development of improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Within INCEFA-PLUS, the effects of mean strain and stress, hold time, strain amplitude and surface finish on fatigue endurance of austenitic stainless steels in light water reactor environments are being studied experimentally, these being issues of common interest to all participants. The data obtained is being collected and standardised in an online environmental fatigue database, implemented with the assistance of an INCEFA-PLUS led CEN workshop on this aspect. Towards the end of the project it is planned that INCEFA-PLUS will develop and disseminate methods for including the new data into assessment approaches for environmental fatigue degradation. This paper provides an overall update on project developments since it was last presented at PVP2018 [1]. As well as being a standalone paper, this document will also serve as an introduction to a companion paper being submitted to cover data generated by the project in more detail [2]. In particular, this paper summarises: • The results for Phases 1 & 2 testing. • The plans for Phase 3 testing. • A summary of emerging sensitivities to, and interdependencies between: o Mean strain and stress, surface finish, strain amplitude and hold time. o Environment. o Material. o Laboratory. • The latest thinking on the direction of the project in its final year. • The latest thoughts on how the project results will be used to advance development of improved assessment guidelines. • A summary of dissemination achieved and planned. • Ideas for work after the end of INCEFA-PLUS.

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INCEFA-PLUS Project: Lessons Learned From the Project Data and Impact on Existing Fatigue Assessment Procedures

Volume 1: Codes and Standards ◽

10.1115/pvp2020-21106 ◽

2020 ◽

Author(s):

Sam Cuvilliez ◽

Alec McLennan ◽

Kevin Mottershead ◽

Jonathan Mann ◽

Matthias Bruchhausen

Keyword(s):

Surface Finish ◽

Environmental Effects ◽

Nuclear Power ◽

Power Plants ◽

Lessons Learned ◽

Fatigue Assessment ◽

Data Points ◽

Project Data ◽

Assessment Procedures ◽

Surface Finish Effect

Abstract The INCEFA+ project (INcreasing Safety in nuclear power plants by Covering gaps in Environmental Fatigue Assessment) is a five year project supported by the European Commission HORIZON2020 programme, which will conclude in June 2020. This project aims to generate and analyse Environmental Assisted Fatigue (EAF) experimental data (approximately 230 fatigue data points generated on austenitic stainless steel), and focuses on the effect of several key parameters such as mean strain, hold times and surface finish, and how they interact with environmental effects (air or PWR environment). This work focuses on the analysis of the data obtained during the INCEFA+ project. More specifically, this paper discusses how the outcome of this analysis can be used to evaluate existing fatigue assessment procedures that incorporate environmental effects in a similar way to NUREG/CR-6909. A key difference between these approaches and the NUREG/CR-6909 is the reduction of conservatisms resulting from the joint implementation of the adjustment sub-factor related to surface finish effect (as quantified in the design air curve derivation) and a Fen penalization factor for fatigue assessment of a location subjected to a PWR primary environment. The analysis presented in this paper indicates that the adjustment (sub-)factor on life associated with the effect of surface finish in air (as described in the derivation of the design air curve in NUREG/CR-6909) leads to substantial conservatisms when it is used to predict fatigue lifetimes in PWR environments for rough specimens. The corresponding margins can be explicitly quantified against the design air curve used for EAF assessment, but may also depend on the environmental correction Fen factor expression that is used to take environmental effects into account.

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The Formulation of Material Characteristics of Austenitic Stainless Steels at Extremely High Temperature

Volume 3B: Design and Analysis ◽

10.1115/pvp2017-65666 ◽

2017 ◽

Author(s):

Kenta Shimomura ◽

Takashi Onizawa ◽

Shoichi Kato ◽

Masanori Ando ◽

Takashi Wakai

Keyword(s):

High Temperature ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Structural Integrity ◽

Austenitic Stainless Steels ◽

Severe Accident ◽

Integrity Assessment ◽

Severe Accidents ◽

Material Characteristics

This paper describes the formulation of material characteristics of austenitic stainless steels at extremely high temperature which meets in some kinds of severe accidents of nuclear power plants. After the severe accident in Fukushima dai-ichi nuclear power plants, it has been supposed to be very important not only to prevent the occurrence of abnormal conditions, i.e. from the first to the third layer safety, but also to prevent the expansion of the accident conditions, i.e. the fourth layer safety[1] [2]. In order to evaluate the structural integrity under the severe accident condition, material characteristics which can be used in the numerical analyses, such as finite element analysis, were required [3] [4]. However, there were no material characteristics applicable to the structural integrity assessment at extremely high temperature. Therefore, a series of tensile and creep tests was performed for austenitic stainless at extremely high temperature which meets in some kinds of severe accidents of nuclear power plants, namely up to 1000 °C. Based on the acquired data from the tests, monotonic stress-strain equation and creep rupture equation applicable to the structural analysis at extremely high temperature, up to 1000 °C were formulated. As a result, these formulae make it possible to conduct the structural integrity assessment using numerical analysis techniques, such as finite element method.

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