ML18267A093
| ML18267A093 | |
| Person / Time | |
|---|---|
| Issue date: | 09/24/2018 |
| From: | Robert Tregoning NRC/RES/DE |
| To: | |
| Shared Package | |
| ML18267A083 | List: |
| References | |
| Download: ML18267A093 (5) | |
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
Gary L. Stevens Technical Executive, EPRI NRC Public Meeting on Environmentally Assisted Fatigue (EAF) Research and Related ASME Activities September 25, 2018 NRC Headquarters - Rockville, MD Overview of EPRI Updated Gap Report
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
Environmentally Assisted Fatigue Gap Analysis and Roadmap for Future Research, November 2012 (Product ID 1026724)
Gap prioritization performed by industry expert panel 21 gaps identified as high priority 7 hypotheses proposed to explain the apparent discrepancy between test data and field experience The intent of the report is to identify knowledge gaps that can be used to direct research efforts Report is publicly available 2012 Gap Report OLD KNOWLEDGE GAPS
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
Environmentally-Assisted Fatigue; Knowledge Gap Analysis - Update and Revision of the EAF Knowledge Gaps (Product ID 3002013214)
Gaps were reviewed in the light of recent research
- Based on direction of industry R&D programs A revised and categorized list of gaps was developed:
- Remove overlap and increase ease of use
- Emphasize collaboration between testing and assessment
- Revised gaps direct research without constraining organizations requirements Publication expected by end of September 2018; report will be publicly available The EAF Knowledge Gaps were recently updated to reflect the most recent research and understanding Updated Gap Report NEW KNOWLEDGE GAPS A: GENERAL ISSUES A1:Plant vs.
NRC Model A2:EAF Database B: S-N DATA &
DESIGN CURVES B1:Material Specific Design Curves B2:Transference Factors on life and stress B3:Weld Material Data and Design C: LWR EFFECTS ON FATIGUE DESIGN C1:Data for Fen Thresholds C2:Transference Factors in LWR C3:Strain Amplitude effect on Fen C4:Mean Stress/Strain effects D: PLANT REALISTIC S-N DATA D1:Complex/
non-isothermal data to support improved asst methods D: Model validation data for other alloys &
BWR D3:Strain Gradient effects and Total Life assessment E: LWR CRACK GROWTH E1:SS Reference Curves E2:C/LAS Reference Curves E3:NBA Reference Curves E4:Plant Relevant Data to support assessment method development F1: PROTOTYPICAL
& COMPONENT TESTING Paper and presentation was given at Fontevraud 9, September 17-20, 2018
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
Since the 2012 EAF Knowledge Gap Report, there has been extensive progress in EAF research aimed at closing some of the key gaps and developing improved assessment methodologies for EAF in LWR environments The main focus has been on austenitic stainless steels in PWR coolant Some of the most significant and promising new assessment methods and supporting data are at differing stages of development:
- Recognition that transference factors differ between air and LWR environments so a proportion of Fen is already included in the ASME III design curve (Fen-integrated, Fen-threshold)
- Weighting models for assessing both fatigue life and crack growth for complex and non-isothermal transients (SNW, WKR)
- Consideration of using lower transference factors on stress and on life
- Use of effective K for crack growth calculation for transients with a compressive portion
- Recognition of strain gradient effects for thermal transients which support the development of a Total Life Assessment methodology A revision of the Knowledge Gap report includes a revised, condensed, and categorized listing of the remaining knowledge gaps
- This publicly available EPRI report is in final publication Conclusions of Updated Gap Report
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
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