ML17037B931

Nine Mile Point Unit 2 - Letter Regarding an Enclosed Progress Review of Program for Evaluation of Geologic Structural Discontinuities as of April 30, 1977 - Cooling Tower Unit

ML17037B931
Person / Time
Site:	Nine Mile Point
Issue date:	05/06/1977
From:	Rhode G K Niagara Mohawk Power Corp
To:	Case E G Office of Nuclear Reactor Regulation
References
Download: ML17037B931 (14)

Text

FORMJ~VuoIiV444IiliI14IIV4AIVllI'VIIIIVIIa41VlNIPVa)NRCDISTRIBUTIONFonP.50DOCI(ETMATERIALVV4liLII'OVIVIIIt'lFILENUMOERTOE.G.CASEUSNRC/LETTERQORIGINALSCOPYQNOTORIZEDgfUNCLASSIFIEDPROPINPUTFORMIROM:NIAGARAMOHAWKPWRCORP.SYRACUSE,NY.G.K.REODEIDATEOFDOCUMENT56/77~DATERECEIVED5/ll/77NUMBEROFCOPIESRECEIVEDDESCRIPTIONltr.transthefollowing.......FNCLOSUREAPPENDIXSUMMARIZINGTPEWORKANDTHE'INTHRPRE-TATIONSOF.APPLICANTSINVESTICATXVEPROGRAM..DQNOTREMOVFIgPsoss)'ABNINEMILEPT/32(4PAGEOS)4'\t~W!',.~~!'r'SAFETYKCKNOWLE>FORACTION/INFORMATIONmrASSXGNEDAD:hE:K$3iTRF'*a:='QCSSSTCv'etcSIGlRANGERSPROJECTIIIANAGER:LICASSTINTERNAL0ISTRIBUT.IOiVREGFXLNDRX&EOELDGOSSXCK&STAFFMIPCCASEIIANAUERIIARLESSPROJECTMANAGFMENTBOYDP~COLLINSHOUSTONPETERSONMELT7.HELTEHF.SSKOVIIOLTIPDRDm(TXC:NSXC:ASLB:ACRSCYSQ1QLDXN&/NRCFORMIIJ6I27II)SYSTEMSSAFETYHEXliEMANSCHROEDERENGINEERINGMACARRYBOSL'AKSI1IWEXLPAWLICKREACTORSAFETYROSSNOVAKROS7TOCZYCHECKAT&XSALTZHANR'UTBERCEXTFANALOISTAIDUTIONNAT,IAB~REGA.XELAPDILCONSULTANTS:IETPI'ANTSYSTEMSTEDFSCO~~AOAXPPOLXTO~ERE'PERATXNGREACTORSSTELLOOPERATXNGTECHEISEMIUTSUAQhERBUTI.EPRDIEBROOVINYl;NDAT~E.U~LRRSO~M~ORNA,JLMKIUB7YdTHLSaJiULLFZENVQQO~QQERiiSTBALLARiDSPANGLERSITSTRC1iGSWIXLLHUL>IANSITEANALYSISVOLLIIERBUNCHJ.COI.LINSKREGERCONTROLNUMUCA

'4IIrh*1l~~a;~f(1s~aw~>0l2rJf4Jl' NIAGARAMOHAWKPOWERCORPORATIONallIII&NIAGARA~MOHAWK300ERIEBOUIEVARDWESTSYRACUSE/II.Y.I3202~,lMay6,1977gavx>>~77il04%KRMM7MMEll:ilL3lINP7;Mr.EdsonG.Case,ActingDirectorOfficeofNuclearReactorRegulationU.S.NuclearRegulatoryCommissionWashington,D.C.20555Re:NineMilePointUnit2DocketNo.50-410

DearMr.Case:

WehavepreviouslyinformedmembersofyourstaffandtheOfficeofInspectionandEnforcementofcertaingeologicfeaturesatourNineMilePointUnit2constructionsite.OnApril11and12,1977,wediscussedadditionaldiscontinuitiesobservedinthecoolingwaterintake-dischargeshaftandon'April29andMay2,1977wediscussedadiscontinuityobservedinthewalls'fadrainageditchconstructedadjacenttoandparalleltooureastpropertyline.Observationsofthesediscontinuitiesandcomparisonwithotheron-sitefeaturesleadtotheconclusionthatthesenewlydiscoveredfeaturesarealsoinactiveandofnoseismo-tectonicsignificance.Thesenewobservationsareentirelyconsistentwiththeearlierinterpretationofotheron-sitefeatures.EvaluationofthesenewobservationswillbeconsideredinthecontextoftheinvestigativeprogramdescribedinmyletterofJanuary24,1977.Theprogramisexpectedtocontinueforseveralmoremonthsandtoaddressthecombinationofgeologicfeaturesnotedatthesitetodate,includingthediscontinuityfoundinthewallsofthedrainageditch.

.~4'0lI~ult4Wrl\41 Mr.EdsonG.Case.U.S.NuclearRegulatoryCommissionPageTwoMay6,1977DuringourmeetingwithmembersofyourstaffonApril14,1977,DamesandMooreprovidedadditionalinformationtosupportearlierinterpretationsofthecoolingtowerfeatures.WehaveattachedheretoanAppendixwhichsummarizestodatetheworkandtheinterpretationsofourinvestigativeprogram.Asindi-catedintheAppendix,DamesandMoorecontinuestointerprettheevidenceassupportingthepositionthatthecoolingtowerfaulthasnoseismo-tectonicsignificanceanddoesnotrepresentahazardtotheoperatingunitsatthesite.Verytrulyyours,NIAGARAMOHAWKPOWERCORPORATIONGeaidK.odeVicePresident-ngineering/sjzAttachmentXc:Mr.T.K.DeBoer,DirectorTechnicalDevelopmentProgramsNewYorkStateEnergyOffice

APPENDXXProgressReviewofProgramforEvaluationofGeologicStruc-turalDiscontinuitiesatNineMilePointasofApril30,1977-CoolingTowerFaultExcavation-ofTrenches-Todateaseriesoffivetrenchesandanexploratroypathavebeenexcavatedacrossthetraceofthefaultexposingtheoffsetsinthebedrockforadistanceofapproximately2500feet(Figure1).TrenchesNo.1and2tothenorthwestofthecoolingtowerareawereexcavatedtobedrockandthefaultzonewasnotpresentateitheroftheselocations.PitNo.1wasexcavatedoverthefaulttobedrock.TrenchesNo.3and4havebeenexcavatedtobedrockandaslotapprox-imately3'x10'x8'eephasbeencutintothebedrockacrossthefaultzoneateachlocation.TrenchNo.5hasbeenexcavatedtobedrockandasimilarrockslotispresentlybeingcut.ThelastsignificantepisodeoffaultingappearstohaveoccurredduringtheCretaceousPeriodwithnotectonicmovementswithinthelast70to100millionyears.Themostrecentsurficialmovementsinvolvingsedimentshavebeenplaced"withinthelast13,000years.Webelieve,atthe'presenttime,thatsufficientevidencecanbeobtainedattheexistingexploratorysitesforanevaluationofthepossiblemechanismsof'surficialdeformationandtheprobabilityofreactivatingthiszone.2.'rill'ing-AdrillingprogramtoexplorethenatureandorrentationofthefaultinghasbeeninprogresssincelateFebruary.TodatetenNXboreholeshavebeendrilledtoanaveragedepthofapproximately200feet.Theseholesarepositionedattwoseparatelocationsandarepatternedtoprofiletherockstrataacrossthefaultzone.Rockcoresanddownholegammaraylogsarebeingcombinedtoproducestratigraphiclogsforeachboringtoaidinthedetailedcorrelationofbed-rockunitsacrossthefault.3.M~apin-GeologicmappingandstructuralanalysisofthebedrockandoverlyingmaterialshasbeencompletedforthewallsandfloorsofTrenchesNo.3,4,and5.ThemappinginPitNo.1istocommenceshortly.SlotscutintothebedrocktoexposethefaultincrosssectionhavebeenmappedinTrenchesNo.3and4;SimilarmappinginTrenchNo.5willbeperformedwhenthatrockslotiscompleted.

eeee 4~SamplinandAnalysis-Rockcoreshavebeenextractedfromboththe.sandstoneandshaleunitsandlaboratorytestedforadeterminationofthestrengthcharacteris-ticsoftheserocks.5.TrenchesNo.3and4andapollenanalysishasbeeninitiatedforcorrelationpurposesandtoascertaintherelativeagesofdepositionofthesedimentsover-lyingthe'edrockfault.Samplesfromtheoverlyingpeatboghavebeentakenandarebeingdatedbyradio-carbonmethods.Rockcoreshavebeencollectedandanalyzedformineral-ogicalcontent.Geochemicalanalyseshavebeenperformedonmineralcrystalssampledfromthefaultzone.Thesedataaidinevaluatingthedepthofburial,temperatureofformationandageofthematerials.6.Geomorphology'andStrati'aohyofGl'acialandPostGlacial'epos'z'ts-Regionalgeology.candgeomorphicliteraturesearcheshavebeenconducted.Thesestudiesinvestigatedthepossibilityofsimilargeologicstructuresintheareaandtherelationship'ofthestructuresatthesitetothegeologichistory.Emphasishasbeenplacedonthegeologichistoryoftheareaforthelast15,000years.lakeandlandlevelsforthisperiodhavebeenplottedandstudiedtoevaluatethereboundcharacteris-ticsresultingfromunloadingtheglacialiceandwaterthatcoveredthearea.Thepossiblerelevanceofpop-upsduringthistimeofunloadingisalsounderinvestigation.7~Stre'ss'ea'surement-Stressconditionsintheregionhavebeenevaluatedandaprogramisunderwaytomeasureinsitustressconditionsatthesite.Themeasurementofstressesinthebedrockutilizestheovercoreandtheovercore/undercoretechniques.Oneovercoreboreholehasbeencompletedtoadepthof95feetanddrillingatasecondlocationisinprogress.8.Sei'smi'ci'ty-Areviewofseismiceventsintheregion1tectoniceventsintheareaanditsrelationshiptothesite.'INTERPRETATIONANDCONCLUSIONS-Dames&Moorebeganitspre-lrmrnaryrnvestrgatronoftttocoolingtowerfaultsoonafteritsSeptember29,1976discovery.OnDecember13,1976adetailedgeologicinvestigationwasinitiated.Thisinves-tigationisongoingandisscheduledtocontinueforseveralmoremonths.Agreatmanyoftheplannedtaskshavebeen

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~~completed.Amajorpartoftheincompletedwork,asofthisdate,isrelatedtotheboringprogram.NXcoreboringsacrossthefaultzonesareapproximately80percentcomplete.Theovercorestressmeasurementsare15percentcompleteandthesurfaceovercore/undercoreprogramisjustgettingunder-way.Thecompletionofthesetaskswillprovideanunder-standingoftheinsitustressfieldanditsrelationshiptopastandanypossiblefuturerecurrenceofmovementatthefaultzone.Ananalysisandevaluationoftheevidencetodatecontinuestosupportmajorportionsofourearlierinterpretation.Thereappeartobethreedistinctmovementsassociatedwiththefaultzone.ThefirstmovementwastheformationofthestrikeslipfaultduringthePaleozoicEra,morethan200millionyearsago.Thisfaultexperiencedabout,3feetofleftlateralstrike-slipmovement.Asecondmovementproducedthemonoclinalflexuring.Analysisofmineralsthatcoatdipslipslickensidessuggestthismovement.mayhaveoccurredduringtheCretaceousPeriod,70to100millionyearsago.Thethirdandlastmove-mentwaspreviouslyjudgedasapop-upalongapre-existingfault.Itischaracterizedbysmoothfoldinginthebedrockclosetothefaultzone,foldedbrecciatedzones,beddingplaneslip,andsmallhigh-anglereversefaultsintheglacialandpost-glacialdeposits.Althoughthesefeatureswereprobablyproducedbythesameconditionsthatarethoughttoproducepop-ups(glacialiceandlakeunloadingandhorizontalstresses),therateofreleaseisconsideredtobedistinctlydifferentfromthatcommonlyassociatedwithpop-ups.WeinterpretthisQifferencetobeaslowenergyreleasethatcouldnotproduceaperceptableseismiceventinsteadofthealmostinstantaneousstressreleasegenerallyassociatedwiththeformationofpop-ups.DamesaMoorecontinuestointerprettheevidenceassupportingthepositionthatthefaulthasnoseismo-tectonicsignificancetothesiteandwefeel,atthistime,thatthereisnoreasontosuggestthatthefaultrepresentsahazardtotheoperatingunitsatthesite.

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