overview of the on-going codification regarding fatigue design of

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Overview of the On -going French Codification Regarding Fatigue Design of Austenitic Stainless Steels With and Without Environmental Effect.

Laurent DE BAGLION; Stéphan COURTIN; Stéphane CHAPU LIOT (AREVA NP SAS; Paris; France)Thomas METAIS; (EDF SEPTEN; Lyon; France)Erlangen; July 07 th, 2016

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Content

L. de Baglion; S. Courtin; T. Métais - Fatigue Desig n with/without EAF - AIEA Fatigue Meeting 07 of July 2016

1.Overview

2.RPP n°2: Modification of the fatigue curve

3.RPP n°3: Environmental Effects Evaluation method

4.Approval process & next steps

5.Conclusion

6.References

� Two Requests for Modification (RM) of the RCC-M submitted la te2014 to AFCEN:� New fatigue curve for austenitic and austeno-ferritic SS;� Incorporation of Environmental Effects on the fatigue life of austenitic and austeno-ferritic SS.

� Given the positive Operating Experience (OPEX) in fatigue a nd inconsistence with other initiatives world-wide, the two req uests formodification aim at:� Incorporate NUREG/CR-6909 findings in the French code;� Take a reasonably conservative stance (new RCC-M curve ~ for mer RCC-M curve);� Integrate representative test results developed in France and abroad (development of an

alternative method for EAF).

� Each RM incorporate the current state of the art in fatigue and adopta reasonably conservative approach.

� These RM will be incorporated in the RCC-M 2016 edition as Rules inProbation Phase (RPP) .

Overview – RCCM Modification Proposal


Evolution of the rules along three aspects (in agreement with international practices)

Update of the mean air curve

Update of the design curve

Calculation of an environmental factor

NUREG/CR-6909 (ANL)

mean air curveCoefficients of

10 and 1.4

1) Fen from NUREG/CR-6909 Rev.1

2) Introduction of the F en-

integrated criteria

RPP n°2 on the SS fatigue curve (Part 2) RPP n°3 on

environmental effects in PWR

(Part 3)

Overview – Contents of the RPP


Content


1.Overview




5.Conclusion

6.References

Factor 10 on the number of cycles selected

� Detailed contents can be seen in PVP2014-28408 & PVP2014-45158.� Comparison with NUREG/CR-6909 Rev.0 et Rev.1:

� Conservative factor selected to remain close to NUR EG/CR-6909 and cover a part of the environmental effects:

NUREG/CR-6909 (2007) Rev. 0NUREG/CR-6909

(2014) Rev. 1French data

Param. Effect

Air PWR Air PWR Param. Effect Air PWR

Data scatter

2.1 - 2.8 2.1 - 2.8 2.1 - 2.8 2.1 - 2.8

Data scatter

2.1 - 2.8 2.1 - 2.8

Am=6.891 & sd=0.417

Am=6.328 & sd=0.462

Am=6.891 & sd=0.417

Am=6.891 & sd=0.417

Am=6.977 & sd=0.352

Am=6.427 & sd=0.392

Surface roughness

2.0 - 3.5 2.0 - 3.5 1.5 - 3.5 1.5 - 3.5 Component effect

2.0 - 3.0 1.5 - 2.5

Scale 1.2 - 1.4 1.2 - 1.4 1.0 - 1.4 1.0 - 1.4

Loading history

1.2 - 2.0 1.2 - 2.0 1.0 - 2.0 1.0 - 2.0 Loading effect 1.0 - 2.0 1.0 - 2.0

TOTAL 11.6 12.4 9.6 9.9 TOTAL 7.0 6.0

RPP n°2 – Factor on life 1/2


RPP n°2 – Factor on life 2/2


Less scatter in the French data points

Model suitable for up to 10 6 cycles (similar to NUREG/CR-6909)

French data

International data

Mean air curve

Mean St. Dev R²

French data NUREG -0.01 0.23 0.78

Japanese data (316 SS)

PVP2009-77115

-0.03 0.20 -

Japanese data (304 SS)

PVP2009-77115

0.08 0.31 -

International data

NUREG 0.09 0.32 0.80

R² from NUREG NUREG - - 0.85

Factor 1.4 on the strain amplitude selected

� Detailed contents can be seen in PVP2014-28409 - « Statistical Analyses of High Cycle Fatigue French Data for Aust enitic SS ».

� Main goal of the publication: Validate the coefficient 1.4 on strain amplitude (material variability) by applying four various sta tistical approaches to the French available data at high number of cycles.

� Four methods used� Prediction intervals;� Wilks percentiles (order

statistics);� Maximum likelihood;� Quantile regression.

RPP n°2 – Factor strain amplitude


RPP n°2 – New design curve proposal


RCC-M Appendix ZI Curve

RCC-M RPP #2 Curve

Content


1.Overview




5.Conclusion

6. References

RPP n°3 – Fen Integrated (F en-int ) definition 1/3


AREVA Experimental campaign (Low Cycle Fatigue Tests) star ted in 2005 on 304Laustenitic stainless steels (already studied in Air) in PWR water environment.

Step 1 (2005-2007): Tests validations in usual conditions ( Polished specimens &Triangular loading signal).

Step 2 (2007-2014): Extended conditions to more representa tive ones:

� Complex loading signals (double thermal shocks) + Ground surface finish.

⇒ Complex mechanisms observed: Loading signal effect + Combination/competition between effects…(Internal R&D tests + 2 PhD thesis to go further in mechanisms).

⇒ Over-conservatism of the NUREG/CR-6909 methodology exacerbated in representative conditions. Anon-negligible part of the PWR water environment effects are covered by the design curve. Notion ofthe (Fen-allowable) factor, now called Fen-integrated factor !

Step 3 (Since 2008): Development & Promotion & Improvement o f the AREVA EAFmethodology.

� Accepted by the STUK for the OL3 EPR in Finland;

� Being reviewed by the NRC in the frame of a Topical Report;

� Accepted/shared and improved with EDF and CEA under the name Fen-integrated methodology.

� Fen-integrated methodology associated to a new design curve for austenitic steels introduced in theRCC-M 2016 edition.


Idea that RCC-M or (ASME) fatigue design curves cov er an appreciable part of the environmental effects, quantified by F en-integrated factor.



Fen-int

Theoretical Fen (NUREG/CR-6909)

Experimental fatigue life

Number of cyclespredicted by the design curve

Margins relating to non-treated effects in tests (Material

variability & Load history)

Proposed values :

� Fen-int ≈ 3 at least .

� Fen-int ≈ 5 for particular thermal chocks.

For each AREVA test, determination of F en-integrated values:


Responsibility of the analysts (ex.:

screening method can be used)

Criteria on the temperature ( ≤200°C)

and strain rate ( ≥0.1%/s)

Additional calculations to evaluate the F enand correct CUF

See details on next slide

RPP n°3 – General Methodology


� Detailed description on how to evaluate Fen : using NUREG/CR-6909 Rev. 1 expressions for austenitic SS:

1

2

1-Simplified assessment: use of conservative

assumption on strain rate and temperature

2-Detailed assessment: (see next slides)

RPP n°3 – Fen calculation description


� Detailed method:� Integral Strain-based method (from item 10-293 of A SME)

� Evaluation on positive strain rate parts only (1)

� Evaluation ignoring gaps between transients (2)

Positive strain rate portions

ε

t (sec)

(1)

(2)

RPP n°3 – Detailed method 1/2


� Detailed method (cont.):� Correction with the Ke factor:

� Calculation of the overall F en :

Method 1 Method 2

Fen-global

RPP n°3 – Detailed method 2/2


RPP n°3 – Criterion & Analysis

� Compare to F en-integrated criteria: F en-integrated = 3 (at least)

If Fen-global ≤ Fen-integrated

If Fen-global > Fen-integrated

� If CUFen > 1, additional analyses can be led:� If the zone is impacted by hot and

cold shock transients only then Fen-integrated = 5.

� If the zone is partially impacted by hotand cold shock transients then:

No correction needed

CUFen = CUF x Fen-global /Fen-integrated


Content


1.Overview




5.Conclusion

6. References

� Main validation steps of the proposal:

ex.: Design Working Group for the RCC-M Code

Working Groups

Sub- Committee

Editorial Committee

Request for Modification (RM) (ex.: Fatigue curves + EAF)

ex.: RCC-M sub-committee

Approval process 1/2


� Main validation steps of the proposal (cont.):� Two Requests for Modification (RM) of the RCC-M sub mitted late 2014 to AFCEN;

� Given the technical extent of the proposals, Design Working Group assembled a special Technical WG (“GTFE” = Working Group on Environmenta l Fatigue);

� “GTFE” gave an overall favorable opinion on the two RM in 2015;

� Validation by the Design WG : December 2015;

� Validation by the RCC-M Sub-Committee: January 2016 ;

� Given the novelty of these rules, these RM are inte grated as RPP (Rules in Probation Phase) in the RCC-M 2016 edition.

Approval process 2/2


� Detailed proposal: see article PVP2016-63127.

� Application of the method: � RPP’s will be applied starting 2017 for the “VD4” ( lifetime extension over 40 years) of 900

MWe NPP’s;� RPP’s are (will be) used for EPR TM licensing: FA3 (France), TSN (China), Hinkley Point

(UK), …

� EAF Testing still ongoing: � AREVA / EDF-SEPTEN tests campaign ( Fen-int factors validation at several Fen-theo values);� EDF R&D testing as part of MODERN Project (“FATCOR 2” loop);� CEA testing such as “Fabime2E”;� AREVA R&D EAF/FCGR tests;� INCEFA+ European project (“INcreasing Safety in NPPs by Covering gaps in

Environmental Fatigue Assessment +” , with 16 partners);

� Proposal as ASME code-case.

Next steps


Content


1.Overview




5.Conclusion

6. References

� Two new RPP’s for fatigue in RCC-M edition 2016: � Austenitic and austeno-ferritic SS fatigue curve:

• In agreement with international initiatives• Construction:

• Mean air curve: NUREG/CR-6909• Coefficient on number of cycles: 10• Coefficient on strain amplitude: 1.4

• Covers also Nickel based alloys (similar to current RCC-M and ASME codes)

� EAF methodology: • Use of NUREG/CR-6909 Rev. 1 formulas and item #10-2 93 of ASME• Take advantage of test results on RCC-M grades (ARE VA tests, etc…)• Introduction of F en-integrated � EAF portion already covered in the fatigue curve• Overall approach with an increasing degree of refi nement

� Perspectives:� Application for “VD4” 900 Mwe;� Application for EPR TM licensing;� Additional testing ongoing : EDF-SEPTEN/AREVA progr am, + EDF / CEA / AREVA tests, …� Proposal as an ASME code-case

Conclusion


Content


1.Overview




5.Conclusion

6. References


Concerning the experimental data (papers):

� J. A. Le Duff et al.; PVP 2008-61894; "Effects of Surface Finish and Loading Conditions on the LowCycle Fatigue Behavior of Austenitic Stainless Steel in PWR environment"; July 27-31, 2008,Chicago, Illinois, USA.

� J. A. Le Duff et al.; PVP 2009-78129; "Effects of Surface Finish and Loading Conditions on the LowCycle Fatigue Behavior of Austenitic Stainless Steel in PWR environment for various strain amplitudelevels"; July 26-30, 2009, Prague, Czech Republic.

� J.A. Le Duff et al.; PVP 2010-26027; “Effect of loading signal shape and surface finish on the LCFbehavior of 304L stainless steel in PWR environment”; July 18-22, 2010, Bellevue, Washington,USA.

� L. De Baglion et al.; PVP 2012-78767, “Influence of PWR Primary Water on LCF Behavior of Type304L Austenitic Stainless Steel at 300°C - Comparison with Results Obtained in Vacuum or in Air”;July 15-19, 2012, Toronto, Ontario, Canada.

� T. Metais, E. Karabaki, J. Solin, L. de Baglion et al.; PVP 2014-28207; "European Contributions toEnvironmental Fatigue Issues; Experimental Research in FRANCE, GERMANY & FINLAND"; July20-24, 2014, Anaheim, USA.

� L. De Baglion et al.; PVP 2014-28329, “LCF Behavior in Air and in PWR Water of a Type 304LAustenitic Stainless Steel Manufactured by Hot Isostatic Pressing Process”; July 20-24, 2014,Anaheim, California, USA.

EAF STUDIESREFERENCES


Concerning the experimental data (papers):

� T. Poulain, L. De Baglion, J. Mendez, G. Hénaff; “Influence of the Strain Rate on the Low CycleFatigue Life of an Austenitic Stainless Steel with a Ground Surface Finish in Different Environments”,Fatigue 2014 , Melbourne.

� L. De Baglion et al.; PVP 2015-45214, “LCF Behavior in Air and in PWR Water of Type 304L and316L Austenitic Stainless Steels Manufactured by Hot Isostatic Pressing Process”; July 19-23, 2015,Boston, Massachussets, USA.

� T. Poulain, L. De Baglion, J. Mendez, G. Hénaff; “Characterization of damage during low cyclefatigue of a 304L austenitic stainless steel as a function of environment (air, PWR environment) andsurface finish (polished, ground)”, XVIII ICMFM 2016, Gijon, Spain.

Concerning the experimental data (PhD Theses):

� L. De Baglion et al. (AREVA); PhD Thesis in French: "Low cycle fatigue behavior and damage of atype 304L austenitic stainless steel in various environments (Vacuum, Air or PWR water) at 300degrees Celsius”; in http://tel.archives-ouvertes.fr/tel-00623190/fr/, Institut P’, June 2011.

� N. Huin et al. (EDF); PhD Thesis in English: "Environmental effect on cracking of a 304L austeniticstainless steel in PWR primary environment under cyclic loading”; Institut P’, February 2013.

� Th. Poulain et al. (AREVA); PhD Thesis in French: "Low cycle fatigue of a type 304L austeniticstainless steel: influence of surface finish and loading signal shape in PWR water environment”;Institut P’, October 2015.



Concerning the engineering analysis and codification acti ons (papers):

� S. Courtin et al.; PVP 2012-78088; "Environmentally Assisted Fatigue Assessment Considering anAlternative Method to the ASME Code Case N-792"; July 15-19, 2012, Toronto, Ontario, Canada.

� T. Metais, S. Courtin et al.; PVP 2013-97203; "French Methodology Proposal For EnvironmentallyAssisted Fatigue Assessment"; July 14-18, 2013, Paris, France.

� T. Metais, S. Courtin et al.; PVP 2014-28408; "Status of the French Methodology Proposal ForEnvironmentally Assisted Fatigue Assessment"; July 20-24, 2014, Anaheim, USA.

� T. Metais, S. Courtin et al.; PVP 2015-45158; "Overview of French Proposal of Updated AusteniticSS Fatigue Curves and of a Methodology to Account For EAF"; July 19-23, 2015, Boston, USA.

� S. Courtin, T. Metais et al.; PVP 2016-63127; “Modifications of the 2016 Edition of the RCC-M Codeto Account for Environmentally Assisted Fatigue”; July 18-22, 2016, Vancouver, Canada.


This references list is of course non-exhaustive an d gather together main (AREVA or AREVA/EDF) EAF studies at the origin or supporting the RPP.


Thanks for your attention.

Questions ?

Proposed values :

Fen-int ≈ 3 at least .

Fen-int ≈ 5 for particular thermal chocks.

RCC-M Appendix ZI Curve

RCC-M RPP #2 Curve

Acknowledgement to all EDF, CEA, AREVA contributors for these developments !

overview of the on-going codification regarding fatigue design of

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