ML18267A090
| ML18267A090 | |
| Person / Time | |
|---|---|
| Issue date: | 09/24/2018 |
| From: | Tregoning R L NRC/RES/DE |
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| Download: ML18267A090 (13) | |
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© 2018 Electric Power Research Institute, Inc. All rights reserved.Jean Smith, Ph.D., P.E.Principal Technical LeaderU.S. Nuclear Regulatory Commission Public Meeting on Environmentally Assisted Fatigue ResearchSeptember 25, 2018Rockville, MarylandWater Chemistry Effects on EAF,EAF Under Plant-Like Conditions (Hold Time Effects), andEAF Short Crack Growth 2© 2018 Electric Power Research Institute, Inc. All rights reserved.ContentWater Chemistry Effects on EAF (KHNP)EffectofZnadditiononEAFofType316SSinPWRwaterEAF Under Plant-Like Conditions (KHNP)Hold Time Effects on EAF of Type 316SS in PWR waterEAF Short Crack Growth (Wood) 3© 2018 Electric Power Research Institute, Inc. All rights reserved.Zn Effect on EAF BackgroundZinc additions to PWR primary water is known to stabilize the oxide structure and increase PWSCC resistance of nickel-base alloysIn Alloy 182:Zn addition reduced PWSCC initiation for all levels of dissolved hydrogen (DH)Zn addition modified the oxide morphology and composition more strongly in normal and high DH conditionsIn Type 316 stainless steel an iron-nickel-chromium (Fe-Ni-Cr) spinel forms at the EAF crack tipHypothesis: Zinc addition in PWR primary water will result in crack tip oxide modification in Type 316 SS and mitigate EAF 4© 2018 Electric Power Research Institute, Inc. All rights reserved.Zn Effect on EAF Test MatrixObjectiveEstablish a PWR environmental fatigue database of Type 316 SS for Zn addition combined with dissolved hydrogen conditionTest program includes reference tests in air and PWR waterPWR water tests includeHold time (0 or 400 sec)Zinc addition (0 or 30 ppb)DH control (25 or 50 cc/kg)TestMaterial316 AusteniticStainless SteelTest conditionReferencePWRAirPWRNumber of test specimen (ea)4416Test EnvironmentAirPWRenvironmentTemperatureRT / 325C325CControl typeStraincontrol (ASTM E606)Strainamplitude (%)0.4Strainrate (%/s)0.004 (0.04)Hold time (sec)0 /400Water ChemistryDO-<5 ppbDH (cc/kg)2525/50Zinc (ppb)0 / 30Conductivity (RT)pH (RT)6.3 5© 2018 Electric Power Research Institute, Inc. All rights reserved.Zn Effect on EAF Fatigue LifeFatigue life comparisonWith no hold: Fatigue life increased but within the data scatterWith 400 s hold: Fatigue life increased significantly and is comparable to Ni-base alloy (w/out hold) 6© 2018 Electric Power Research Institute, Inc. All rights reserved.Zn Effect on EAF Crack TipCrack tip behaviorAnalysis by several methods (TEM, ToF-SIMS, AED, XPS) shows Zn is incorporated into crack tip oxideLess metal dissolution occurs -> relative sharp crack tipPWR with 400 second holdPWR + 30 ppb Zn with 400 second hold 7© 2018 Electric Power Research Institute, Inc. All rights reserved.Zn Effect on EAF OxidesOxide stability enhancementFilm resistance increasedDefect density decreasedResulting oxide film is more stable and protective 8© 2018 Electric Power Research Institute, Inc. All rights reserved.Zn Effect on EAF Upcoming PlansNext steps for this programKAIST FacilityZn & High DH condition testKHNP FacilityReference testsHigh DH condition testFurther AnalysisOxide identification: diffraction pattern analysis to confirm Zn incorporation into oxideFuture project ideasStrain Rate EffectVery low strain rate vs. hold time effect0.001%/s strain rateConfirm strain rate dependency of Zn effectHold time variationFatigue life variation as a function of hold time (100s, 400s, 800s)Zinc effect in carbon and low-alloy steel 9© 2018 Electric Power Research Institute, Inc. All rights reserved.EAF Under Plant-Like Conditions (Hold Time Effects --KHNP)ObjectiveCharacterize the influence of complex loading conditions on fatigue life of austenitic stainless steels in PWR environmentsTest MaterialType 316 Austenitic Stainless SteelAir/PWR (reference)Mixed WaveSpecimens6 total6 total6 totalCase2 each at 3 conditions2 each at 3 different strain rates with 60 second hold time2 each at 3 different strain rates with 300 second hold timeEnvironmentPWR EnvironmentTemperature310 CControlStrain ControlStrain Rate (%/s)0.4/0.04/0.0040.4/0.04/0.0040.4/0.04/0.004Strain Amplitude (%)0.40.40.4Water ChemistryDO< 5 ppbDH25 cc/KgConductivity (RT)< 20-25 S/cm(1200 ppm H3BO3+ 2.2 ppm LiOH)pH (RT)6 -7Solid specimenwith gauge section19.05 mm long x 9.63 mm dia 10© 2018 Electric Power Research Institute, Inc. All rights reserved.EAF Under Plant-Like Conditions (Hold Time Effects --KHNP)Effect of hold-time on EAF life is inconclusive in this test10 11© 2018 Electric Power Research Institute, Inc. All rights reserved.EAF Short Crack GrowthObjectivesFurther the mechanistic understanding of EAF behavior in the short crack regime.Develop an understanding intended to bridge the gap between fatigue endurance and Paris Law crack growth to better enable prediction of total (Stage I + Stage II) life 12© 2018 Electric Power Research Institute, Inc. All rights reserved.EAF Short Crack GrowthCommissioning tests in air and in PWR water completeProved ability to grow cracks using 0.228 mm broaches at R = 0.05. Demonstrated ability to generate DCPD data in RT, 300 ºC Air and 300 ºC water (simulated primary coolant chemistry)Improved predictions between DCPD readings and fractographic measurements achieved during trial programNoted that FEA needed to be undertaken to provide material specific K values.2018 test matrixCompare CGRs in air and PWR environment (1,2,3)Study rise time effects for environmental enhancement (2,3)Compare broach depths (4,5)Test MatrixTestBroach Depth (mm)EnvironmentLoadingTrial 10.228Air (RT)Trial 20.228Air (RT)Trial 30.228Air (300 °C)Trial 40.228Water (300 °C)10.228Air (300 °C)20.228Water (300 °C)30.228Water (300 °C)40.1-0.15*Air (300 °C)50.1-0.15*Water (300 °C)6TBD*Broach depth to be determined by FEA calculations of K/KBeach marks to be inserted after 6 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />; R=0.3 or 0.5Simulated PWR primary water: 300ºC, 2 ppm Li, 500 ppm B as boric acid, 30 -40 cc/kg H2 13© 2018 Electric Power Research Institute, Inc. All rights reserved.