ML21041A450
| ML21041A450 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 02/09/2021 |
| From: | Herr M Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CCN: 21-14 | |
| Download: ML21041A450 (13) | |
Text
Exelon Generation.
CCN: 21-14 February 9, 2021 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station (PBAPS) Unit 2 Renewed Facility Operating License No.
DPR-44 NRC Docket No. 50-277 10CFR 50.55a
Subject:
Submittal of the lnservice Inspection (ISi) Owner's Activity Report (OAR) for the 23rd Refueling Outage for Unit 2 Attached is the ISi Owner's Activity Report for the 23rd refueling cycle covering ISi activities that span the third period of the 4th ISi inspection interval and the first period of the 5th ISi inspection interval for Unit 2. This report is submitted in accordance with 10CFR 50.55a(b)(2)(xxxii); the ASME Section XI, Article IWA-6200; ASME Code Case N-532-4; and ASME Code Case N-532-5.
In addition to the OAR-1 report, the following two evaluations are also being submitted:
- 1. EC 633079 Moisture Barrier Inaccessible Areas Evaluations is being submitted in accordance with 1 OCFR 50.55a(b)(2)(ix)(A)(2).
- 2. EC 632895 CH-MB Flaw Evaluation is being submitted in accordance with ASME Section XI, Paragraph IWB-3114.
If you have any questions or require additional information, please contact Ben Jordan at 717-456-4583.
Sincerely, Matthew J. Herr Site Vice President Peach Bottom Atomic Power Station Attachment cc:
USNRC, Regional Administrator, Region 1 USNRC, Senior Resident Inspector, PBAPS W. DeHaas, Commonwealth of Pennsylvania S. Seaman, State of Maryland B. Watkins, PSEG
Page 1 of 3 FORM OAR-1 OWNERS ACTIVITY REPORT Report Number P2R23 Plant Peach Bottom Atomic Power Station, 1848 Lay Road, Delta, PA 17314 Unit No.
2 Commercial Service Date July 5, 1974 Refueling Outage Number P2R23 (if applicable)
Current Inspection Interval ISI = Fourth & Fifth Inspection Interval / CISI = Second & Third Inspection Interval (1st, 2nd, 3rd, 4th, other)
Current Inspection Period Third & First Inspection Period (ISI and Containment ISI)
(1st, 2nd, 3rd )
Edition and Addenda of Section XI applicable to the Inspection Plans ASME Section XI 2001 Ed. w/2003 Add. (4th ISI/2nd CISI Interval), ASME Section XI 2013 Edition (5th ISI/3rd CISI Interval)
Date and Revision of Inspection Plans 4th/2nd Interval Plans, ER-PB-330-1001 Rev. 0 (8/30/18) 5th/3rd Interval Plans, ER-PB-330-1001 Rev. 1 (12/13/18), Rev. 2 (10/3/19) Rev. 3 (8/13/2020) Rev. 4 (10/16/2020)
Edition and Addenda of Section XI applicable to repair/replacement activities, if different than the inspection plans Same as above Code Cases used:
N-532-5, N-613-2, N-638-7, N-702, N-716-1, N-747, N-798, N-800 CERTIFICATE OF CONFORMANCE I certify that (a) the statements made in this report are correct; (b) the examinations and tests, meet the Inspection Plan as required by the ASME Code,Section XI; and (c) the repair/replacement activities and evaluations supporting the completion of P2R23 conform to the requirements of Section XI (refueling outage number)
Signed Benjamin Jordan, ISI Program Owner Date 2/5/2021 (Owner or Owners designee. Title)
CERTIFICATE OF INSERVICE INSPECTION I, the undersigned, holding a valid commission issued by the National Board of Boiler and Pressure Vessel Inspectors and employed by Hartford Steam Boiler Inspection and Insurance Company have inspected the items described in this Owner's Activity Report, and state that, to the best of my knowledge and belief, the Owner has performed all activities represented by this report in accordance with the requirements of Section XI.
By signing this certificate neither the Inspector nor his employer makes any warranty, expressed or implied concerning the repair/replacement activities and evaluation described in this report. Furthermore, neither the Inspector nor his employer shall be liable in any manner for any personal injury or property damage or a loss of any kind arising from or connected with this inspection.
Commissions (Inspectors Signature)
(National Board Number and Endorsement)
Date
Page 2 of 3 TABLE 1 ITEMS WITH FLAWS OR RELEVANT CONDITIONS THAT REQUIRED EVALUATION FOR CONTINUED SERVICE Examination Category Examination Item Number Item Description Evaluation Description E-A E1.30 Damaged Moisture Barrier As found condition evaluated by engineering under EC 633079 and determined to be acceptable.
Corrective measures were taken under WO 04997289.
E-A E1.11 External corrosion and coating loss on external Torus External corrosion and coatings conditions evaluated by engineering under A/R 04379999-02 and determined acceptable with no corrective measures required.
B-A B1.22 CH-MB multiple new indications that were not acceptable per the IWB-3510 table As found condition evaluated by engineering under EC 632895 and determined to be acceptable in accordance with IWB-3600.
B-P B15.10 Leak found at N-16A nozzle during the B-P Pressure Test As found condition repaired and one cycle justification per EC 632907.
Relief Request I5R-14 and evaluations submitted to NRC.1 1.
Relief Request submitted on November 4, 2020 (ML20309B020). Flaw evaluations submitted on November 24, 2020 under ML20329A345 and ML20329A346.
Page 3 of 3 TABLE 2 ABSTRACT OF REPAIR/REPLACEMENT ACTIVITIES REQUIRED FOR CONTINUED SERVICE Code Class Item Description Description Of Work Date Completed Repair/Replacement Plan Number 1
N-16A Nozzle Performed half nozzle repair based on leak found during B-P pressure test.
11/14/2020 20-113
Engineering Change Company Name :
EXELON GENERATION CO.,LLC Print Date:
11/08/2020 EC Number :
0000632895 001 Status/Date :
CLOSED 11/08/2020 Facility :
PEA PEACH BOTTOM ATOMIC POWER STATION Type/Sub-type:
EVAL MECH Page:
1 EC
Title:
ASME SECTION XI FLAW EVALUATION - WELD CH-MB P2R23 INDICATIONS 16 AND 28 Mod Nbr :
KW1: SR KW2: KW3: KW4: KW5:
Master EC :
N Work Group :
Temporary :
N Outage :
Y Alert Group:
A5452NESDM Aprd Reqd Date:
WO Required :
Image Addr :
Exp Insvc Date:
Adv Wk Appvd:
N Alt Ref. :
Expires On :
08/04/2023 Auto-Advance:
Y Priority :
Auto-Asbuild :
N Caveat Outst:
N Department :
Discipline :
Resp Engr :
TRAVIS GEHMAN Location :
Units Fac Unit Description PEA 02 UNIT TWO Outages Fac Unit Outage Description PEA P2R23 UNIT 2 REFUEL, CYCLE 23 Systems Fac System Description PEA 04 REACTOR PRESSURE VESSEL & INTE
Engineering Change Print Date:
11/08/2020 EC Number :
0000632895 001 Status/Date :
CLOSED 11/08/2020 Facility :
PEA Type/Sub-type:
EVAL MECH Page:
1 EC
Title:
ASME SECTION XI FLAW EVALUATION - WELD CH-MB P2R23 INDICATIONS 16 AND 28 Mod Nbr :
KW1: SR KW2: KW3: KW4: KW5:
Master EC :
N Work Group :
Temporary :
N Outage :
Y Alert Group:
A5452NESDM Aprd Reqd Date:
WO Required :
Image Addr :
Exp Insvc Date:
Adv Wk Appvd:
N Alt Ref. :
Expires On :
08/04/2023 Auto-Advance:
Y Priority :
Auto-Asbuild :
N Caveat Outst:
N Department :
Discipline :
Resp Engr :
TRAVIS GEHMAN Location :
Milestone Date PassPort Name Req By 110-PREPARE EC 11/06/2020 E028493 GEHMAN TRAVIS APPROVED 120-REVIEW EC 11/07/2020 RUFOBX RUFO BRIAN APPROVED I performed an independent review of this revision. I agree with the inputs, methodology, and conclusion.
210-DEPT RVW-EP 11/08/2020 E114373 JORDAN BENJAMIN APPROVED ISI Program review performed by Ben Jordan, PBAPS ISI Program Owner 300-APPROVE EC 11/08/2020 U001JL7 LAVERDE JULIAN APPROVED
EC632895Rev.0 Page1of3 TITLE:ASMESectionXIFlawEvaluation-WeldCHMBP2R23Indications16and28 ThisEngineeringTechnicalEvaluationwaspreparedinaccordancewithCCAA309101Rev.15.AnHUAA1212 Rev.10RiskRankingwasperformedwiththefollowingresultsandcompensatingmethods:
ConsequenceRiskFactor:
[M.1]-Errorsintroducedwithoperationalconsequences:ISIprogramreview HumanPerformanceRiskFactors:
[H.4]-Knowledge/experiencegaps:DesignreviewerhasISIexperience
[H.5]-Firsttimetask:Performwalkthroughoftask Thisevaluationwillrequireanindependentreviewasitaffectssafetyrelatedcomponents.
Revision1:ThisrevisiondoesnotimpacttheclassificationasaTechnicalEvaluation,theHUAA1212review performed,orthereviewrequirementsofrevision0.
1.0REASONFOREVALUATION/SCOPE AscheduledISIinspectionoftheUnit2RPVheadduringP2R23identifiedindicationsinweldCHMBthatdonot meettheacceptancecriteriaofASMESectionXITableIWB35101andrequireanalysispertherequirementsof IWB3600todetermineiftheyareacceptableforcontinuedservice(IRs4380356/4382547).Thistechnical evaluationwillusea2002GEHitachiflawevaluationreport[Ref.1](referredtoasthe2002reportinthis evaluation)ofweldCHMBtodetermineiftheP2R23flawsareboundedbytheprevious2002evaluationand acceptableforcontinuedservice.ThismethodologymirrorsthatusedtoevaluateandacceptaCHC2weldflaw inP2R18[Ref3].
Revision1:IR4382547documentsanadditionalunacceptableweldCHMBindication(#28)perASMESectionXI TableIWB35101.Thistechnicalevaluationrevisionwillanalyzeindication28IAWtherequirementsofIWB 3600todetermineifitisacceptableforcontinuedservice.Revision1changesareindicatedwithrevisionbarsin theleftmargin.
2.0DETAILEDEVALUATION ThereactorpressurevesselclosureheadatPeachBottomAtomicPowerStation,Unit2wasultrasonically(UT) examinedduringP2R23inaccordancewiththePeachBottomFifthTenYearISIIntervalPlan,whichis committedtothe2013EditionofASMESectionXI[Ref.4].
ThereweremultipleindicationsnotedintheClosureHeadMeridionalWeld(CHMB).Allbuttwoofthe indicationseitherweredeemedacceptablebasedontheASMESectionXI,TableIWB35101orbyprevious evaluation.Indications#16and#28fromtheP2R23inspectionrequireevaluationperIWB3600toallow continuedoperation.Indication16waspresentedinGEReportCNFISI007(Attachment1)[Ref.2]and indication28waspresentedinGEReportCNF012(Attachment2)[Ref.5].
In2002,GEHitachiperformedaflawevaluationformultipleindicationsonweldCHMB.Thistechnical evaluationwillusethatreport(G080VC301)todetermineifthenewindicationsarebounded.Inordertodo so,thefollowingitemswereevaluated/confirmed:
- 1. FlawSize/Type:
The2002reportevaluated16differentsurfaceflawsthatwerenotacceptableperASMESectionXI, TableIWB35101.P2R23flaw#16hasalengthofL=0.9anddepthofa=0.16(a/L=0.1778).There
EC632895Rev.0 Page2of3 aremultipleindicationsinthe2002reportthatboundtheP2R23flaw,withthelargesthavingalengthL
=3.75anddeptha=0.25(a/L=0.0667).
Indication16isasurfaceflawwithalengthtodepthaspectratiothatislargerthanthebounding2002 reportflaw.Thestressintensityfactor(K)increasesasaspectratiodecreases,asseeninTable41ofthe 2002report.Therefore,theflawsize,type,andstressintensityfactorforP2R23indication16are boundedbythe2002report.
Revision1:P2R23flaw28hasalengthofL=2.0anddepthofa=0.15(a/L=0.075).Thissurfaceflaw hasalengthtodepthaspectratiothatislargerthanthebounding2002reportflaw.Thestressintensity factor(K)increasesasaspectratiodecreases,asseeninTable41ofthe2002report.Therefore,the flawsize,type,andstressintensityfactorforP2R23indication28areboundedbythe2002report.
2.
Sincethe2002evaluation,PBAPShasundergoneanextendedpoweruprate(EPU).However,itwas confirmedthattheboundingloadsdidnotchangesincethe2002report:
Thefollowingassumptionswereusedinthe2002reportandremainvalid.
Theboltuptemperatureis70F.Thisassumptionisacceptableperambienttemperatureconditions atboltup.
Thetestpressureandtemperatureare1050psiand169F.VerifiedperSTO080500(680)2.
3.
Sincethe2002evaluation,PBAPShasreceivedasubsequentlicensetoallowoperationupto80years.
The2002reportevaluatedaboundingfatiguecrackgrowthof0.025usingthe60yearlicenseatthe time.Thefatiguecrackgrowthcanconservativelybeincreasedusingthelongeroperationperiodby scalingoutthetimeperiod:0.025x80/60=0.033.Thisgrowthisinconsequentialandwouldremain boundedbythe2002flawreferencedabove.
4.
ItwasverifiedthattheapplicablesectionsofASMESectionXIdidnotchange.Therefore,the2002 reportmethodologyremainsvalid.
Basedontheaboveconsiderations,P2R23indications16and28areboundedinflawcharacteristicsand evaluationmethodperformedin2002GEreportG080VC301.
3.0CONCLUSION
S/FINDINGS PerIWB3132.3,AcceptanceByAnalyticalEvaluation,P2R23Indications16and28onweldCHMB,asdetailed intheAttachment1and2reports,havebeenevaluatedasdescribedinIWB3600andmeettheacceptance criteriaofIWB3600.WeldCHMBisacceptableforcontinuedserviceandispredictedtobeacceptablethrough endofplantlife.InaccordancewithIWB2420,successiveexamrequirementswillneedtobeevaluated.Thisis beingtrackedviaassignment0438035602.
PerIWB3134(b)thisanalyticalevaluationmustbesubmittedtotheregulatoryauthorityhavingjurisdictionat theplantsite(i.e.NRC).Assignment0438035603hasbeengeneratedtotrackthissubmittal.
Revision1:Anotehasbeenaddedtotheaboveassignmentstoreferencetheadditionofindication28tothis technicalevaluation.
EC632895Rev.0 Page3of3
4.0REFERENCES
1.G080VC301,TheEvaluationofIndicationsinPeachBottomUnit2VesselClosureHeadforContinued Operation.
2.CNFISI007GEReport,CHMBClosureHeadMeridionalWeld 3.EvaluationA111853002,TechnicalEvaluationforU2RPVClosureHeadtoFlangeWeld(CHC2)Indication 4.ASMEBoilerandPressureVesselCode,SectionXI,RulesforInServiceInspectionofNuclearPowerPlant Components,2013Edition.
5.CNF012,GEReportCHMBCustomerNotificationForm
5.0ATTACHMENTS -CNFISI007GEReport:Indication16(3Pages) -CNF012GEReport:Indication28(2Pages)
6.0MILESTONES SeePassportforMilestones.
7.0ImpactReview
ISIprogramengineerperformedaninterfacereviewandsignedaPassportMilestone.
PerreviewofCCAA102,therewerenoadditionalimpactsidentified.
Revision1:AnISIprogramengineerperformedaninterfacereviewandsignedaPassportMilestone.
Therearenoadditionalimpactsfromrevision1ofthistechnicalevaluation.
Engineering Change Print Date:
12/08/2020 EC Number :
0000633079 000 Status/Date :
MODIFIED 12/08/2020 Facility :
PEA Type/Sub-type:
EVAL STRU Page:
1 EC
Title:
ASSESS UNIT 2 MOISTURE BARRIER DAMAGE IMPACT ON DRYWELL VESSEL Mod Nbr :
KW1: SR KW2:
KW3:
KW4:
KW5:
Master EC :
N Work Group :
Temporary :
N Outage N
Alert Group:
A5452NESDM Aprd Reqd Date:
WO Required :
Image Addr :
Exp Insvc Date:
Adv Wk Appvd:
N Alt Ref. :
Expires On :
09/03/2023 Auto-Advance:
Y Priority :
Auto-Asbuild :
N Caveat Outst:
Y Department :
Discipline :
Resp Engr :
PAUL R KESTER Location :
Milestone Date PassPort Name Req By 110-PREPARE EC 11/23/2020 U000PRK KESTER PAUL APPROVED 120-REVIEW EC 12/03/2020 U000JV6 VACANTE JOSEPH APPROVED I have independently verified this Engineering Technical Evaluation and con cur with the conclusions herein. All comments have either been incorporate d or resolved between the originator and verifier. Additional engineering analysis regarding the corrosion mechanisms and environment are deemed appr opriate and are provided by reference within this document.
210-DEPT RVW-EP 11/23/2020 E114373 JORDAN BENJAMIN APPROVED 300-APPROVE EC 12/08/2020 U000A5M HUBER AMY APPROVED I have reviewed the technical eval and concur with the specified conclusion. This evaluation meets the ASMESectionXIrequirementsofIWE2500(d)and10CFR50.55a(b)(2)(ix)(A)(1).
Ben Jordan (11/23/20)
EC633079rev.0 Page1of3 Scope:
ThisevaluationappliestoPeachBottomUnit2,addressingtheconditiondiscoveredduringP2R23.The conditionbeingevaluatedisthatthemoisturebarrier,wherethedrywellbottomelevationconcrete floorslababutsthesteelcontainmentvessel,wasfounddegraded.Themoisturebarrierisessentiallya largebeadofcaulkthatsealstheinterfacewheretheconcretefloorstopsatthesteelcontainment vesselwallasitrisesabovetheElevation11911floorelevation.Refertodwg.S193detail1(ref.4).
ThisinterfaceformsthecircularperimeteroftheElevation11911floorslab.A4longsectionofthe perimeterssealantmaterialwasfoundtobeunadheredanddislodgedfromthejointfromazimuth145 toazimuth157.Thiswouldleavethejoint,andthepotentialcrevicebetweentheconcreteandsteel belowit,opentoanywaterthatleakedwithinthedrywell(excludingtheundervesselarea).Thewater hasnodrainagepathfromthere,soitcouldremaininthecreviceandcorrodethesteelcontainment vessel.Thisareaofthevessel,theinternalsteelsurfacebeneaththeconcreteflooratElevation119 11,isclassifiedasinaccessible.
ThescopeofthisEC,asdirectedinAR4379124Assignment02,istoevaluatetheasfoundconditionand determinetheacceptabilityoftheinaccessibleareasinaccordancewith10CFR50.55a(b)(2)(ix)(A).That codestates:
(A) Metal containment examinations: First provision. For Class MC applications, the following apply to inaccessible areas.
(1)
The applicant or licensee must evaluate the acceptability of inaccessible areas when conditions exist in accessible areas that could indicate the presence of or could result in degradation to such inaccessible areas.
(2)
For each inaccessible area identified for evaluation, the applicant or licensee must provide the following in the ISI Summary Report as required by IWA-6000:
(i) A description of the type and estimated extent of degradation, and the conditions that led to the degradation; (ii) An evaluation of each area, and the result of the evaluation; and (iii) A description of necessary corrective actions.
Evaluation:
Thedrywellisasteelcontainmentvesselwithvaryingthickness.Thethicknessforeachsectionis designedtoprovidetheneededcapacityforallpressure,weight,thermal,seismicandotherstresses.
Thisthicknessmustbemonitoredtoensurethatsufficientcapacityremainsthroughoutitsdesignlife.
Thebottomportionofthedrywellisconsideredtobeinaccessiblebecauseitisadjacenttoconcrete onbothsides.Sincethethicknessandconditionofthesteelinthisareacannotbedirectlymeasuredor
EC633079rev.0 Page2of3 visuallymonitored,thisevaluationprovidesaqualitativeassessmentofthepotentialformaterialloss duetocorrosionfromexposuretowater.
Themoisturebarrieraddressedhereisasealantappliedtotheperimeterofthedrywellconcrete floor,atitsinterfacewiththesteeldrywellshell.Thatsealantisintendedtopreventwaterormoisture fromcomingintocontactwiththedrywellshellbelowtheelevationofthefloorsurface.Corrosionin thisareawouldbedifficulttodetectduetoitsinaccessibility.Withthedamagediscoveredtothe sealantduring2R23andtheknownleakageinthedrywell,itmustbeassumedthatwaterhasinfiltrated theinterfaceoftheconcreteandthedrywellshelltosomedegree.Thepotentialforthistocause corrosionofthedrywellshellisthereforeassessed.
Thechemistryofconcreteisverybasic(highpH),whichprotectsthesteelincontactwithitfromrusting, muchliketherebarcontainedwithinconcreteisprotectedfromrusting.Thatchemicalprocess,andits applicabilitytothisspecificconfigurationhavebeendescribedindetailintheattachmenttopreviousIR 2561844A03(ref.3).ItremainsapplicabletothecurrentconcernbeingaddressedfortheUnit2 drywellinP2R23.Inaddition,oxygenmustbepresentforthedrywellsteeltooxidize.Thedrywellis purgedwithnitrogenmostofthetime,limitingthepresenceofoxygen.Theareaofdrywellsteelthat wouldhavethehighestexposure,andthereforevulnerabilitytomoistureandoxygenwouldbeatthe locationofthemoisturebarrier.Thislocationisexposedtooxygenduringarefuelingoutage,andis wherewaterleakageinthedrywellcouldcollect(intheareasofadamagedmoisturebarrier).The inaccessibleportionofthedrywellbelowthefloorssurfacecouldalsobeexposedtomoisture,butit wouldnothaveasmuchexposuretooxygen,ifanyatall.Thislineofhighestvulnerabilityistypically observedwithsubmergedsteel,havingrustatthewaterlinebutnotaboveorbelowit.Thereisno visualevidenceofanysignificantcorrosionintheareaswherethemoisturebarrierhasseparated.The observedsteelatthedislodgedareaofthemoisturebarrierhadlittletonosurfacecorrosionpresent.
Sincethisisthemostlikelyareaforcorrosion,itcanbeconcludedthattheareabeneaththelevelofthe floorisinasgoodofaconditionastheexposedareas,orbetter.
NotethatthisconditionhasbeenevaluatedindetailforotherUnitsinthepast.Thosepastevaluations areincludedinthereferencesbelow.Thoseevaluationswerereviewedanddeterminedtobe applicableforthesubjectconditionevaluatedhere.Theessentialargumentsfromthoseevaluationsare providedabove,whilesomeofthemoredetailedexplanationshavenotbeenrepeatedhere.Seethe referencesbelowformoredetailsasneeded.
Tospecificallyaddresstherequireditems(i),(ii)and(iii)fromthecodeabove:
(i) Thetypeofdegradationbeingevaluatedisthepotentialinternalsurfacecorrosionofthedrywell containmentvesselbelowthesurfaceofthe11911concretefloor.Basedontheinformation aboveandinthecitedreferences,theestimatedextentofdegradationis,atworst,minorsurface corrosionwithnosignificantlossofthicknessinallinaccessibleareas.Thisisbasedontheminor areasofsurfacecorrosionvisibleattheinterfacebeingtheworstlevelofcorrosion,duetothe chemicallyprotectivepropertiesoftheconcreteandtheabsenceofanenvironmentcontaining oxygenbelowthefloorssurface.Theconditionthatleadtothepotentialforcorrosionisthe portionofdamagedmoisturebarrier.Theexactcauseofthedamagedmoisturebarrierisnot known,butitissuspectedtobeduetohightemperaturefluidleakage(oilorwater)causingaloss ofadhesion.
EC633079rev.0 Page3of3 (ii) Theinformationabove,andthesupportingdetailsinthereferencesindicatethattherewouldbe nosignificantcorrosionontheinaccessiblesurfaceofthedrywellcontainmentvessel.Itis concludedthattherewouldbenolossofthickness,andthereforethecontainmentremainsfully qualified.
(iii)
Themoisturebarrierwasrestoredtoitsrequiredconfiguration(ref.5).Noadditionalcorrective actionsarerequired.
==
Conclusion:==
Thefailedportionofmoisturebarrierandtheresultingpotentialforwaterhavingseepedintothe interfacebetweenthefloorslabandthedrywellshelldonotpresentathreatofanysignificant corrosionoccurringtothedrywellshell.Thedeficienciesinthemoisturebarrierhavebeencorrectedto preventfurtherexposure.Noadditionalactionisrequired.
Administrative:
ThisisatechnicalevaluationpreparedinaccordancewithCCAA309101rev15.Itaddressesasafety relatedstructureandthereforerequiresanindependentreview,managerapprovalandtransmittalto RecordsManagement.AnyrequiredISIprogramimpactsareintendedtobeaddressedbytheprogram ownerunderAR4379124A03andA04.AMilestonesignoffhasbeenrequestedoftheISIprogram ownertoensurethatthisresponseaddressestheprogramsremainingneeds.BasedonareviewofCC AA102,thisevaluationhasnootherprogram,procedureorotherdocumentationimpactsanddoesnot requireinterfacereviewbyanyothergroup.ApplicationofHUAA1212withJulianLaverdeindicated thehighestapplicableconsequenceriskfactorhasaLowseveritylevel(L.2),andonehuman performance/processriskfactor(P.6)isapplicabletothescopeofthisevaluation.Theuncertaintyof criticalparametersismitigatedthroughinvestigationofpast,similarevaluationsandthetechnical detailssupportingthem.Theresultingriskrankis1,andexistingprocessreviewsareappropriate.This evaluationisnotcomplex,andnosupplementalreviewsarerequiredorwarranted.
References:
- 1. PassportEC621863rev.0,Unit3moisturebarrierdamagediscoveredduringP3R21
- 2. PassportAR4066968,Unit3moisturebarrierdamagediscoveredduringP3R21
- 3. PassportAR2561844,Unit3moisturebarrierdamagediscoveredduringP3R20
- 4. DrawingS193rev.4,ReactorVesselFoundation
- 5. WO0499728902,RepairofMoistureBarrierduringP2R23 Attachments:
None