ML18267A084
| ML18267A084 | |
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|---|---|
| Issue date: | 09/24/2018 |
| From: | Tregoning R L NRC/RES/DE |
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| ML18267A083 | List: |
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| Download: ML18267A084 (8) | |
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© 2018 Electric Power Research Institute, Inc. All rights reserved.Gary L. StevensTechnical Executive, EPRINRC Public Meeting on Environmentally Assisted Fatigue (EAF) Research and Related ASME ActivitiesSeptember 25, 2018NRC Headquarters -Rockville, MDStatus of Previous EPRI EAF Efforts 2© 2018 Electric Power Research Institute, Inc. All rights reserved.Previous presentations at this meeting have provided updates of many of Fatigue Usage Gradient and Life Factor Concept (Gosselin)Alternative Approaches for Simplified Elastic-Plastic Analysis (Raganath)Fatigue Limit of Stainless Steel for Use in Vibration Evaluation (Raganath)Corrosion Fatigue Crack Growth of Low Alloy Steel in BWRs (Raganath)Non-Isothermal EAF Testing for 316 Stainless Steel in Simulated PWR Environment (Asada)Hold Time and Water Chemistry Effects Testing (Smith)EAF Short Crack Growth Testing (Smith)EPRI EAF Component Testing (Smith)research:1.Probabilistic Determination of Margins in ASME Code Section III CUF Calculations2.Fatigue Crack Growth Rates for Austenitic Stainless Steels in BWR Environments3.BWR Subsequent License Renewal EAF Database4.International Collaboration Group 3© 2018 Electric Power Research Institute, Inc. All rights reserved.This project develops a simplified engineering approach (based on probabilistic methods) that quantifies the uncertainties of inputs in CUF and CUFencalculationsThis approach may be used in CUF andCUFen sensitivity analyses to identify andrank those inputs and their uncertaintiesthat control component CUF and CUFenand their uncertaintiesDetailed knowledge of the CUF andCUFen uncertainties in the underlyingdeterministic framework can help to:Focus and direct efforts to eliminateunnecessary conservatismReduce associated costs of (re)design,(re)analysis, inspections, and mitigation effortsto meet the unspecified margins associated with acceptance limitsEPRI Report No. 3002012326, Basis and Method for AssessingAdequacy and Margins for Fatigue Under the Effects of WaterEnvironment and Sources of UncertaintyMay 2018 (publicly available at www.epri.com)The technical report was provided to the ASME Code Section IIIFatigue Steering Committee for their use to potentially refineSection III CUF calculation methods as a part of their Fatigue Action PlanProbabilistic Determination of CUF Margins 4© 2018 Electric Power Research Institute, Inc. All rights reserved.In the wake of the publication of ASME Code Section XI Appendix L (Flaw Tolerance) in 2008, a need arose for updated fatigue crack growth (FCG) rates in water environments for most Class 1 nuclear component materialsASME Code Case N-809, Reference Fatigue Crack Growth Rate Curves for Austenitic Stainless Steels in Pressurized Water Reactor Environments, was approved in 2015, and has been successfully used in at least two NRC-approved flaw tolerance submittals to-dateCode Case N-809 has also been used applications supporting calculations for weld overlay repairs conducted using Code Cases N-504 and N-740-2EPRI funded completion of the technical basis document and sample calculations for N-809Additional efforts are needed to develop other FCG rate curves for other materials and other environmentsThis project is developing FCG rates for austenitic stainless steels in BWR environmentsThis project will revise Code Case N-809 to extend its application to BWR environmentsThis project began earlier this year; data collection is in processProject outputs will be an ASME Code Section XI Code Case and a Technical ReportAnticipated completion: 2019BWR FCG Rates for Stainless Steels 5© 2018 Electric Power Research Institute, Inc. All rights reserved.As part of the revision to BWRVIP RPV Inspection and Evaluation Guidelines for life extension, EAF results were compiled for all BWRs that submitted 60-year LRAs and performed EAF evaluationsThe resulting database provides an overall snapshot of the work needed to address EAF for the BWR fleet for SLRExtensive database(over 500 components!)Majority (76.7%) are acceptable for 80 yearsAn additional 16.4% can use refined analysis todemonstrate acceptability (same as those usedfor 60 years)Remaining 6.8% require other methods for acceptabilityOther methods that already exist or are underdevelopment will likely produce satisfactory resultse.g., flaw tolerance, LF/GF approach, revised KeTherefore, completion of ongoing analytical projects is important to address BWR fleet needs for SLRThis project is complete and the results will be documented in an Appendix to BWRVIP-316, Reactor Pressure Vessel Inspection and Evaluation Guidelines for Long Term Operation (to be published in December 2018)All Data ShownBWR EAF Database for 80 Years 6© 2018 Electric Power Research Institute, Inc. All rights reserved.EPRI hosts an EAF International Collaboration GroupOriginal motivations for forming this group:During an EPRI Conference in Summer of 2013 (San Francisco), several observations were identified on differences between European EAF work and the U.S. situation A subsequent meeting was held in January 2014 (France) between EDF, Rolls-Royce and AMEC to discuss exchanges on future test programs and ways of working together on alternative environmental fatigue and propagation methodsThe subsequent discussions recognized that there are mutual benefits to have a common approache.g., data exchange, testing to fill gaps, avoiding duplication, analytical round robin studies, benchmarking of methods, mechanistic understanding, and joint lobbying of industryThe purpose of this collaboration is to:Periodically meet to exchange EAF information and dataCoordinate research efforts to the extent practicalReview on-going research and provide constructive input and directionInternational Collaboration Group (1/2) 7© 2018 Electric Power Research Institute, Inc. All rights reserved.There are currently 7 participating organizations:1.EPRI2.Rolls-Royce3.Wood Group (formerly AMEC Foster Wheeler)4.Framatome5.Électricité de France SA (EDF)6.Bechtel Marine Propulsion Corporation Naval Nuclear Laboratory (Bettis site)7.Mitsubishi Heavy Industries (MHI)All 7 organizationshave signed a Non-Disclosure Agreement (NDA) to facilitate exchange of information and dataThis group meets approximately once each yearThe last meeting was inDecember 14, 2017(Paris, France)The next meeting is September 26-27, 2018(Washington, DC)International Collaboration Group (2/2) 8© 2018 Electric Power Research Institute, Inc. All rights reserved.