RegulatoryguidesareissuedtodescribeandmakeavailabletothepublicsuchinformationasmethodsacceptabletotheNRCstaffforimplementingspecificpartsoftheNRC’sregulations,techniquesusedbythestaffinevaluatingspecificproblemsorpostulatedaccidents,anddataneededbytheNRCstaffinitsreviewofapplicationsforpermitsandlicenses.Regulatoryguidesarenotsubstitutesforregulations,andcompliancewiththemisnotrequired.MethodsandsolutionsdifferentfromthosesetoutintheguideswillbeacceptableiftheyprovideabasisforthefindingsrequisitetotheissuanceorcontinuanceofapermitorlicensebytheCommission.Thisguidewasissuedafterconsiderationofcommentsreceivedfromthepublic.Commentsandsuggestionsforimprovementsintheseguidesareencouragedatalltimes,andguideswillberevised,asappropriate,toaccommodatecommentsandtoreflectnewinformationorexperience.WrittencommentsmaybesubmittedtotheRulesandDirectivesBranch,ADM,U.S.NuclearRegulatoryCommission,Washington,DC20555-0001.Regulatoryguidesareissuedintenbroaddivisions:1,PowerReactors;2,ResearchandTestReactors;3,FuelsandMaterialsFacilities;4,EnvironmentalandSiting;5,MaterialsandPlantProtection;6,Products;7,Transportation;8,OccupationalHealth;9,AntitrustandFinancialReview;and10,General.Singlecopiesofregulatoryguides(whichmaybereproduced)maybeobtainedfreeofchargebywritingtheDistributionServicesSection,U.S.NuclearRegulatoryCommission,Washington,DC20555-0001,orbyfaxto(301)415-2289,orbyemailtoDISTRIBUTION@NRC.GOV.ElectroniccopiesofthisguideandotherrecentlyissuedguidesareavailableatNRC’shomepageat(DraftwasissuedasDG-1101)SITEINVESTIGATIONSFORFOUNDATIONSOFNUCLEARPOWERPLANTSA.INTRODUCTIONThisregulatoryguidedescribesfieldinvestigationsfordeterminingthegeological,engineering,andhydrogeologicalcharacteristicsofaprospectiveplantsite.Itprovidesguidancefordevelopinggeologicinformationonstratigraphy,lithology,andstructureofthesite.Theinvestigationsrecommendedprovidedatadefiningthestaticanddynamicengineeringpropertiesofsoilandrockmaterialsatthesiteandtheirspatialdistribution.Thus,thesiteinvestigationsprovideabasisforevaluatingthesafetyofthesitewithrespecttotheperformanceoffoundationsandearthworksunderanticipatedloadingconditions,includingearthquakes.In1996,theNuclearRegulatoryCommission(NRC)issuednewregulationsconcerningsiteevaluationfactorsandgeologicandseismicsitingcriteriafornuclearpowerplantsinSubpartB,“EvaluationFactorsforStationaryPowerReactorSiteApplicationsonorAfterJanuary10,1997,of10CFRPart100,“ReactorSiteCriteria.”Inparticular,10CFR100.20(c),100.21(d),and100.23ofPart100establishrequirementsforconductingsiteinvestigationsfornuclearpowerplantsforsiteapplicationssubmittedafterJanuary10,1997.Safety-relatedsitecharacteristicsareidentifiedindetailinRegulatoryGuide1.70,StandardFormatandContentofSafetyAnalysisReportsforNuclearPowerPlants.”RegulatoryGuide4.7,GeneralSiteSuitabilityCriteriaforNuclearPowerStations,discussesmajorsitecharacteristicsthataffectsitesuitability.1.132-2ThisregulatoryguidedescribesmethodsacceptabletotheNRCstaffforconductingfieldinvestigationstoacquirethedataongeologicalandengineeringcharacteristicsofasiteneededforanuclearpowerplantsiteapplication.Theguideincludesrecommendationsfordevelopingsite-specificinvestigationprogramsandguidanceforconductingsubsurfaceinvestigations.Theguideisbeingrevisedtoincorporatenewerpracticesandinsights.AreportwrittenbytheU.S.ArmyCorpsofEngineersstaff,NUREG/CR-5738,wasusedasatechnicalbasisforthisguideandmaybeconsultedfordetailsofprocedures.Theappendicestothisguidearetakenfromthatpublication.LaboratorytestsandanalysesfordeterminingsoilandrockpropertiesaredescribedinRegulatoryGuide1.138,“LaboratoryInvestigationsofSoilsforEngineeringAnalysisandDesignofNuclearPowerPlants.”RegulatoryGuide1.165,“IdentificationandCharacterizationofSeismicSourcesandDeterminationofSafeShutdownEarthquakeGroundMotion,”definesinvestigationsrelatedtoseismicity,faults,andvibratorygroundmotion.Thisguidedoesnotdealwithvolcanologicorhydrologicinvestigations,exceptforgroundwatermeasurementsatthesite.ConsiderationsforfloodingaredescribedinRegulatoryGuide1.59,“DesignBasisFloodsforNuclearPowerPlants.”Theinformationcollectionscontainedinthisregulatoryguidearecoveredbytherequirementsof10CFRPart50,whichwereapprovedbytheOfficeofManagementandBudget,approvalnumber3150-0011.IfameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalidOMBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.B.DISCUSSIONPURPOSEThepurposeofthesiteinvestigationsdescribedinthisguideistoacquirethegeotechnicaldataneededtodesignnuclearpowerplantfoundationsforsafetyandperformance.Theyshoulddefinetheoverallsitegeologytothedegreenecessarytounderstandsubsurfaceconditionsandtoidentifypotentialgeologichazardsthatmayexistatthesite.Localgroundwaterconditionsmustalsobedefined.Investigationsforhazardssuchasfaultoffsets,land