ML22236A547
| ML22236A547 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/24/2022 |
| From: | Clifford Munson NRC/NRR/DEX |
| To: | |
| Lee S, NRR/DORL/LPL4 | |
| References | |
| Download: ML22236A547 (12) | |
Text
Current Diablo Canyon Seismic Evaluation Dr. Cliff Munson Senior Level Advisor for Siting U.S.N.R.C
Outline
- Background
- NearTermTaskForceHazardAssessments
- DiabloCanyonSeismicHazardandRisk Evaluations
- References
NRCRegulations-SafeShutdown Earthquake
- Nuclearpowerplantstructures,systemsand componentsimportanttosafetyarerequired tobeabletowithstandeffectsofnatural phenomenasuchasearthquakes
- Safeshutdownearthquakegroundmotion (SSE)isthevibratorygroundmotionforwhich safetyrelatedstructures,systems,and componentsmustbedesignedtoremain functional
NRCRegulationsforSitingFacilities
- 10CFRPart100- Reactorsitecriteria includinggeologyandseismology
- Specifiessitinginvestigationsandanalysesin ordertodetermineSafeShutdownEarthquake groundmotion(SSE)
- Priorto1997SSEdeterminedusingDeterministic approach
- Groundmotionfrommaximumearthquakeusedto determineSSE
DCPPSeismicDesignSpectra Hosgri faultM7.2at4.5km(1971)
LongTermSeismicProgramMarginAnalysis(1978)
DoubleDesignEarthquakeM7.25at20km(1969)
DesignEarthquake(1969)
NRC2012RequestforHazard Assessments
- InresponsetoMarch11,2011,GreatEast JapanearthquakeandtsunamiNRCrequested seismichazardassessmentsforallU.S.NPPs
- Requestspecifieduseofpresentday NRC regulationsandguidancetoassesshazard
- PG&Esubmitteditsseismichazardassessmentto theNRCin2015
CurrentNRCRegulationsandGuidance forSeismicHazards
- Post1997GeologicandSeismicsitingregulations providedin10CFR100.23
- 100.23requiresdetermining sliprates forlocaland regionalfaults
- 100.23requiresincorporatinguncertainty intodetermining SSE
- RegulatoryGuide1.208describesperformancebased approachtodefinesitespecificgroundmotion
- SpecifiesaProbabilistic approachratherthanDeterministic
- Usesriskinformedapproachtodevelopsiteground motionthatachievesperformancegoalsinstandardASCE 43
DCPPSeismicHazardAssessment
- PG&Eevaluateddatafrommultipleoffshore andonshoregeophysicalandgeotechnical investigationstodevelop
- Seismicsourcemodel
- Seismicgroundmotionmodel
- Amplificationofseismicgroundmotionsdueto localsoilandrockproperties
DCPPSeismicHazardAssessment
- PG&Edevelopedadetailedseismicsourcemodel fortheregion
- Faultsliprates
- Faultgeometriesandlocations
- Maximummagnitudesforfaults
- Multiplefaultrupturescenarios
- PG&Edevelopedaseismicgroundmotionmodel toassessgroundmotionamplitudesfrom multiplefaults
- PG&Eadjustedthegroundmotionmodeltoaccount forthelocalsiteeffects
DCPPGroundMotionResponse Spectrum(GMRS)
DCPPSeismicRiskEvaluation
- BasedontheresultsoftheseismichazardreevaluationPG&E performedaseismicprobabilisticriskassessment(PRA)
- Determinedseismicfragilitiesofstructuresandcomponents
- Performedsoilstructureinteractionanalyses
- Evaluatedsystemaccidentsequences
- Evaluatedcontainmentperformance
- BasedonitsreviewofthePG&ESeismicPRA,theNRCstaff concludedthatPG&Efollowedtheappropriateguidanceand adequatelyaddressedtheeffectsofthereevaluatedhazard ontheplant.
References
- DetailedsummaryofDiabloCanyonSeismic HazardAssessmentisprovidedinSection3.3 ofNUREG/KM017ML21344A126
- PG&ESeismicPRAML18120A201
- NRCStaffAssessmentofSeismicPRA ML18254A040