ML18267A098
| ML18267A098 | |
| Person / Time | |
|---|---|
| Issue date: | 09/24/2018 |
| From: | Robert Tregoning NRC/RES/DE |
| To: | |
| Shared Package | |
| ML18267A083 | List: |
| References | |
| Download: ML18267A098 (12) | |
Text
© 2018 Electric Power Research Institute, Inc. All rights reserved.
Jean Smith, Ph.D., P.E.
Principal Technical Leader U.S. Nuclear Regulatory Commission Public Meeting on Environmentally Assisted Fatigue Research September 25, 2018 Rockville, Maryland EPRI Collaboration on EAF Component Testing Project Overview
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing Objectives:
Understand the effect of light water environments on the fatigue life and resultant CUF on component materials, Reconcile the differences between the current CUF methodology results and the fleet operating experience with respect to EAF failures, and Provide the technical basis for an improved CUF analytical methodology for EAF Program jointly funded by EPRI, EDF, Rolls-Royce, Naval Nuclear Labs
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Test Component Test Material
- Type 304L stainless steel compliant with ASME BPVC IIA and RCC-M SA-312 specifications
- As-received surface condition
- Thorough characterization of test material Chemical composition Metallurgical evaluation Mechanical testing (including fatigue)
Test Environment
- PWR primary water
- 325 °C to 38 °C to allow for thermal transients
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Test Fixture Test fixture designed to accommodate different test component geometries and loading methods to facilitate extension to other PWR, BWR, and new plant components Straight pipe, multiple-stepped pipe, component with wetted-surface notches Thermal strains applied without mechanical loading Preliminary Fixture Design
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Proposed Transients
- Simulates sudden injection of cold water into a hot PWR nozzle pipe during a turbine roll
- High surface strain is expected to readily initiate cracks
- Environmental effects may not be observed do to the high strain rate
- Thermal shock equivalent to ~ 333,000-344,000 °C/h produced by rapid injection of a slug of cold water (38°C) into hot pipe (325°C) over 1 to 3 seconds and reverse transient Transient #1 - Thermal Shock
- Crack initiation and growth under this moderate strain, strain rate, and gradient to provide intermediate data required to validate the best fit model
- Moderate ramp of ~39,000-41,000 °C/h shall be produced by ramping from hot (325°C) to cold (38°C) over ~25s and reverse transient Transient #2 - Moderate Ramp
- Slow-rising strain simulates normal plant cooldown of a PWR nozzle pipe and is expected to allow assessment of environmental enhancement effects
- Slow ramp of ~10,000 °C/h produced as a slow decrease from hot (325°C) to cold (38°C) over ~100s and reverse transient Transient #3 - Slow Ramp
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Overall Process Five-year test program consists of four phases Program begins 2018 and finishes in 2022 FEA Modelling and Design
- Define component parameters
- Define transient parameters
- Component FEA model outputs
- Predict fatigue behavior Commissioning
- Thermal and strain FEM benchmarking
- NDE calibration
- FEA alignment
- NDE crack siding calibration
- Revise fatigue predictions Testing
- Initiate fatigue cracks
- ET for crack detection
- Propagate fatigue cracks
- UT for crack growth monitoring
- Post-test examinations Integration into FEA Models
- Calculate CUF (crack initiation
- Calculate through-wall crack growth
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - FEA Modelling and Design Repeat process to ensure fatigue crack initiation/growth
- Changing fluid transient parameters
- Modifying component Geometry
- Adding stress raisers (ID notches)
- Applying mechanical loads Commissioning Define Component Parameters
- Component Geometry
- Notch Geometry
- Material Parameters Define Transient Parameters
- Water transient parameters
- Fluid parameters Component FEA Model Outputs For each of the four components and three water transients
- Water transient temperature as a function of time and distance from inlet
- Metal wetted surface and thru-wall temperature and stress/strain state in test components f(time, thru-wall position, axial distance)
Predict Fatigue Behavior
- Predict fatigue crack initiation and crack growth rate
- Apply NUREG/CR-6909 Rev. 1 to predict life Commissioning
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Commissioning Fabricate Test Components Construct Test Fixture Upgrade Flow Loop Thermal & Strain FEM Benchmarking Install 4 instrumented components Perform water transients Acquire detailed thermal and strain data for input into FEA model NDE Calibration Baseline NDE data Initiate crack via Transient #1 Inspect with ET Grow crack with Transient #3 Monitor with UT NDE Crack Sizing Calibration Post-test examination to align NDE methods with actual crack depths FEA Alignment Adjust FEA model inputs (material and fluid properties) and FEA model parameters Re-calculate predicted wetted surface and thru-wall thermal and strain history Iterate until the FEM matches experimental values Revise Fatigue Predictions
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Test Process Test Set-Up 4 test components Baseline NDE Initiate Fatigue Cracks Test 1: Thermal Transient
- 1 (thermal shock)
Test 2: Thermal Transient
- 2 (moderate ramp)
NDE Inspections for Crack Initiation Periodic ET from ID Grow Fatigue Cracks Test #1: Thermal Transient
- 1 (thermal shock)
Test #2: Thermal Transient
- 3 (slow ramp)
NDE Inspections for Crack Growth Encoded UT from OD Test Termination Criterion Reached Post-test NDE, destructive exams, and calculations
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Integration into EAF Models Calculate CUF (Initiation)
Analyses to align a calculated CUF = 1.0 to initiation of a crack in a test component Calculate Through-Wall Crack Growth Analyses to align predicted crack growth with measured crack growth in a test component The difference between the calculated number of cycles that result in CUF = 1.0 and the measured test cycles to produce a fatigue crack will be used to calculate a factor to represent the difference between predicted fatigue life using a laboratory specimen fatigue curve and the fatigue life of actual components The difference between the number of cycles that cause fatigue crack growth to depths observed in the testing and the test cycles as a function of crack depth will be used to calculate a factor to represent the difference between the calculated fatigue crack growth and the fatigue crack growth of actual components
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
EAF Component Testing - Summary Comprehensive program including FEA modeling and design, commissioning (NDE calibration and FEA alignment),
testing (two sets of test conditions on four specimens), and EAF modeling Bridge the gap between small specimen, separate-effects testing and operating plant components Define factors for fatigue life and fatigue crack growth to allow transference of small specimen data to plant components
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© 2018 Electric Power Research Institute, Inc. All rights reserved.
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