ML14230A911
| ML14230A911 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 08/18/2014 |
| From: | Dunn D S NRC/NMSS/SFST |
| To: | |
| Goshen J M | |
| Shared Package | |
| ML14230A903 | List: |
| References | |
| TAC L24475 | |
| Download: ML14230A911 (16) | |
Text
AgingManagementProgramAging Management Program Example for Stress Corrosion CrackingDarrellS.DunnDarrell S. DunnMeeting to Discuss the Request for Additional Information Responses Regarding the Calvert Cliffs Independent Spent pggppFuel Storage Facility License Renewal July 17, 2014 Stress Corrosion Cracking BackgroundInformationBackground Information *304 and 316 Stainless steels are susceptibletochloridestresssusceptible to chloride stress corrosion cracking (SCC)-Sensitization from welding increases susceptibility-Crevice and pitting corrosion can be precursors to SCC-SCC possible with low surface chloride concentrations 2/3oftherequirements*Welded stainless steel canisters have sufficient through wall tensile residual stresses for SCCAthiSCCfldd2/3 of the requirements for SCC are present in welded stainless steel *Atmospheric SCC of welded stainless steels has been observed-Component failures in 16-33 years-Estimated crack growth rates of 0.11 canisters gto 0.91 mm/yr2 Regulatory Basis*10 CFR 72.42(a), 72.240(c): TLAAs that demonstrate that ITS SSCs will continue to perform their intended function for the period of extended operation.AdescriptionoftheAMPformanagementofissuesassociatedA description of the AMP for management of issues associated with aging that could adversely affect ITS SSCs.*Guidance: NUREG-1927 AMP Elements:1.Scope of the Program2.Preventive Actions 3.Parameters Monitored/Inspected6.Acceptance Criteria7.Corrective Actions 8.Confirmation Process 4.Detection of Aging Effects 5.Monitoring and Trending9.Administrative Controls10.Operating Experience3 AMP Element 1 ScopeoftheProgramScope of the Program NUREG-1927: The scope of the program should include the specific structuresandcomponentssubjecttoanAMR*Welded stainless steel dry storage canistersFabricationandclosureweldsstructures and components subject to an AMR-Fabrication and closure welds -Weld heat affected zones-LocationswheretemporarysupportsorfixtureswereLocations where temporary supports or fixtures were attached by welding-Crevice locations -Surface areas where atmospheric deposits preferentially occursSurfaceareaswithalowerthanaveragetemperature-Surface areas with a lower than average temperature 4 AMP Element 2PreventativeActionsPreventative ActionsNUREG-1927: Preventive actions should mitigate or prevent the applicableagingeffects*Aging Management Program (AMP) is for conditionmonitoringapplicable aging effectscondition monitoring. -Preventative actions are not presently incorporated into existing dry storage canister designs*Future designs or amendments could include -Surface modification to impart compressive residual ffstresses on welds and weld heat affected zones-Materials with improved localized corrosion and SCC resistanceresistance5 AMP Element 3ParametersMonitored/InspectedParameters Monitored/InspectedNUREG-1927: Parameters monitored or inspected should be linked to theeffectsofagingontheintendedfunctionsoftheparticularstructure*Canister surfaces, welds, and weld heat affected the effects of aging on the intended functions of the particular structure and component,,zones for discontinuities and imperfections *Size and location of localized corrosion (e.g., (gpitting and crevice corrosion) and stress corrosion cracks*Appearance and location of atmospheric deposits on the canister surfaces6 AMP Element 4DetectionofAgingEffects(1/2)Detection of Aging Effects (1/2)NUREG-1927: Define method or technique, frequency, sample size, datacollection,andtimingtoensuretimelydetectionofagingeffects*Qualified and demonstrated technique to detect evidence oflocalizedcorrosionandSCC:data collection, and timing to ensure timely detection of aging effectsof localized corrosion and SCC:-Remote visual inspection, e.g. EVT-1, VT-1, VT-3, or Eddy Current Testing (ET) may be appropriatePdidttifidiiiSCCldi*Pending detection findings, sizing SCC would require volumetric methods7 AMP Element 4DetectionofAgingEffects(2/2)Detection of Aging Effects (2/2)*Sample sizep-Minimum of one canister at each site-Canisters with the greatest susceptibility *Data Collection-Documentation of the examination of the canisterLocationandappearanceofdeposits-Location and appearance of deposits*Frequency-Every5yearsEvery 5 years*Timing of Inspections -Within 25 years of initial loading8 AMP Element 5MonitoringandTrendingMonitoring and TrendingNUREG-1927:Should provide for prediction of the extent of the effects ofagingandtimelycorrectiveormitigativeactions*Document canister condition particularly at welds andcrevicelocationsusingimagesandvideoof aging and timely corrective or mitigativeactionsand crevice locations using images and video that will allow comparison in subsequent examinations *Changes to the size and number of any corrosion product accumulations *Location and sizing of localized corrosion and stress corrosion cracking 9 AMP Element 6 AcceptanceCriteria(1/2)Acceptance Criteria (1/2)NUREG-1927: Acceptance criteria, against which the need for corrective action will be evaluated; should ensure that SSC functions *No indications of: ;are maintained-Pitting or crevice corrosion -Stress corrosion cracking -Corrosion products near crevices -Corrosion products on or adjacent to fabrication welds, closureweldsandweldsfortemporarysupportsorclosure welds, and welds for temporary supports or attachments10 AMP Element 6 AcceptanceCriteria(2/2)Acceptance Criteria (2/2)*Locations with corrosion products require additional examination for localized corrosion and/or SCC*Size of the area affected and the depth of penetration if localized corrosion and/or SCC is identifiedidentified*Canisters with localized corrosion and/or SCC mustbeevaluatedforcontinuedserviceinmust be evaluated for continued service in accordance with ASME B&PV Code Section XI IWB-3514.1 and IWB-3640 11 AMP Element 7CorrectiveActionsCorrective ActionsNUREG-1927:Corrective actions, including root cause determination andpreventionofrecurrence,shouldbetimely*Supplemental inspections to determine the extentofconditionatthesiteand prevention of recurrence, should be timelyextent of condition at the site *Subsequent inspections of canisters with indications*Canisters that do not meet the prescribed evaluation criteria must be repaired or removed pfrom service12 AMP Element 8ConfirmationProcessConfirmation ProcessNUREG-1927:Confirmation process should ensure that preventive actions are adequate & appropriate corrective actions have been *Licensee Quality Assurance Program consistent with10CFR72SubpartGor10CFR50qpppcompleted & are effectivewith 10 CFR 72 Subpart G, or 10 CFR 50 Appendix B*Ensure that inspections, evaluations, and p,,corrective actions are completed in accordance with the Site Specific or General Licensees CorrectiveActionProgram(CAP)Corrective Action Program (CAP)-Extent of condition-Evaluation for continued service-Repair, replace, mitigation actions13 AMP Element 9AdministrativeControlsAdministrative ControlsNUREG-1927: Administrative controls should provide a formal review andapprovalprocess*Licensee Quality Assurance Program consistent with10CFR72SubpartGor10CFR50and approval processwith 10 CFR 72 Subpart G, or 10 CFR 50 Appendix B*Trainingrequirementsforinspectors*Training requirements for inspectors*Records retention requirements14 AMP Element 10OperationalExperienceOperational ExperienceNUREG-1927:Include past corrective actions; provide objective evidencetosupportadeterminationthattheeffectsofagingwillbe*NoreportedcasesoflocalizedcorrosionorSCCinevidence to support a determination that the effects of aging will be adequately managed so that the SSC intended functions will be maintained during the period of extended operation*No reported cases of localized corrosion or SCC in welded stainless steel canisters*Atmospheric deposits on canister surfaces have been observed *Several reported cases of chloride induced SCC from atmosphericdepositsobservedinoperatingreactorsatmospheric deposits observed in operating reactors (NRC Information Notice 2012-20)*Laboratory and field test data on conditions necessary for yychloride induced SCC and SCC growth rates 15 AcronymsAcronymsAMP: Aging management program TLAA: time limiting aging analysisAMR: Aging management reviewASME B&PV code: American Society ITS: Important to safety SCC: Stress corrosion crackingyof Mechanical Engineers Boiler and Pressure Vessel code CAP: Corrective action programgSSC: Structures systems and componentspgCFR: Code of Federal RegulationsEVT1:Enhancedvisualtesting1VT-1: Visual Testing-1 (ASME B&PV code Section XI, Article IWA-2200) VT3:VisualTesting3(ASMEB&PVEVT-1: Enhanced visual testing-1(Boiling water reactor vessels and internals project, BWRVIP-03)VT-3: Visual Testing-3 (ASME B&PV code Section XI, Article IWA-2200)16