ML14182A103

July 1, 2014 NRC Slides for Public Meeting with TVA - NTTF 2.1 - Seismic Reevaluation - GMRS

ML14182A103
Person / Time
Site:	Watts Bar
Issue date:	07/01/2014
From:	Japan Lessons-Learned Division
To:	Tennessee Valley Authority
Balazik M F, NRR/JLD, 415-2856
References
Download: ML14182A103 (26)

Text

NearTermTaskForceNear-Term Task Force Recommendation 2.1 Seismic Hazard EvaluationEvaluationTennesseeValleyAuthorityTennessee Valley AuthorityJuly 1, 2014 References for Meeting*Licensee Presentation Slides -ML14182A099*NRC Presentation Slides -ML14182A103PbliMtiAdML14167A164*Public Meeting Agenda -ML14167A164*Meeting Feedback Form (request from mfb@nrc.gov)

• May 9, 2014, NRC letter regarding Seismic Screening dPiititiRltftldtUSand Prioritization Results for central and eastern US Licensees(ML14111A147)*May 21, 2014, NRC memo providing preliminary staff groundmotionresponsespectraforcentralandground motion response spectra for central and eastern Licensees(ML14136A126)*Meeting Summary to be issued within 30-day Meeting IntroductionPurpose: support information exchange and begin dialog to havecommonunderstandingofthecausesoftheprimaryhave common understanding of the causes of the primary differences between the preliminary NRC and licensee seismic hazard resultsBkdNRCdliiihdi

Background:

NRC and licensee seismic hazard require resolution to support a final seismic screening decision and to support related follow-on submittalsOutcomes: *Begin NRC and licensee resolution to support regulatory decisionsanddevelopmentofseismicriskevaluationsdecisions and development of seismic risk evaluations, as appropriate*Establish resolution path, including timelines and identificationofpotentialinformationneedsidentification of potential information needs Look-ahead:Potential Next Steps*NRCwillconsiderthemeetinginformationNRC will consider the meeting information*Potential paths:-LicenseesubmitssupplementalinformationLicensee submits supplemental information based on public meeting dialog-NRC staff issues a request for informationq-Licensee sends a revision or supplement to the seismic hazard report*NRC completes screening review and issues the final screening determination lttletter WattsBarNuclearPlantWatts Bar Nuclear PlantRasool AnooshehpoorOffice of ResearchJuly1,2014July 1, 2014

Screening GlGeology*The site is located in the Tennessee section of Valley andRidgeProvinceoftheAppalachianhighlandsand Ridge Province of the Appalachian highlands.*In Tennessee, the Rome Formation and Conasauga, Knox and Chickamugagroups make up the majority of bdkbedrock.*Sedimentary rocks from Pennsylvanian to Cambrian age, predominant with those of Cambrian and gpOrdovician age.*Folds involving stratified Paleozoic rocks with great differencesinhardnessdifferences in hardness.*At Watts Bar the bedrock is 2000ft thick Middle Cambrian ConasaugaGroup (alternating shale and limestone)limestone).

Site Geology

~706 ftControl Point at 664 ft Control PointNRCSubmittalSSE Control Point at elevation 664 ft.SSE Control Point at elevation 664 ft.

VsProfile DevelopmentNRCCtilittSubmittalShlitibdContinuous velocity measurements at 7 boreholes in FSAR at the top 100 ftwere used to develop the Vsprofile. Shear wave velocities were based on SASW and Birdwell velocity measurements (AMEC, 2013).pVmedian=5704 ft/s, ln=0.134ThisisingeneralagreementwithThis is in general agreement with the General Atomics (1974) estimates.

Figure 2.5-70, FSAR(reproduced)

Shear wave velocity data from seven boreholes (FSAR)

VsProfiles Aleatory Uncertainty in VsProfilesNRCSubmittalNRC30 Randomizations Using USGS "A" Site Conditions Submittal30 Randomizations Using USGS "A" Site Conditions ln= 0.25 Upper 50 ft.ln=0.15Below50ft.ln= 0.25 Upper 50 ft.ln=0.15Below50ft.ln 0.15 Below 50 ft.ln 0.15 Below 50 ft.

Epistemic Uncertainty in VsProfilesNRCSubmittalApplied a scale factors of 1.14 to the base case profile at the Applied a scale factor of 1.25 to the base case profile for ptop 100 ft, and 1.31 from 100 ft to 1000 ft(Reference rock)pdevelopment of the upper and lower case profiles Watts Bar ComparisonSSE Control PointDepth to VS-referenceNon-Linear/DampingppgLicenseeNRC StaffLicenseeNRC StaffLicenseeNRC StaffAt the base of the reactor foundationAt the base of the reactor foundation1)592 ft 2)936 ft~1000 ftEPRI-Rock or Linear (low-strainEPRI-Linear, no damping foundation(el. 664 ft)foundation(el. 664 ft)strainEPRIRock damping)NRCkappa,withonelayer(1000ft)overref.rockLicensee kappa ProfilekappaBase0.0070.0100.016Lower0.0070.0110.018NRC kappa, with one layer (1000 ft) over ref. rock ProfileTotalkappaUpper500ftBalanceP10.0120.0050.0065Lower0.0070.0110.018Upper0.0060.0100.016P20.012*1.680.0070.0144P30.012/1.680.0040.0060P40.0130.0050.0083P50013*168000700168P50.013*1.680.0070.0168P60.013/1.680.0040.0060Epistemic Uncertainty = 1.68

Primary DifferencesVelocity profiles:TVA used two sets of 3-velocity profiles. The reference rock depthisat592ftinonecaseand936ftintheotherdepth is at 592 ftin one case and 936 ftin the other.NRC used three velocity profiles and depth of 1000 ftto reference rock.Low strain damping: TVAused~3%dampingintheupper500ft.NRCusedkappaTVA used 3% damping in the upper 500 ft. NRC used kappa in the upper 1000ft to account for dampingTVA used a factor of 1.68 about P1 and P4 total kappasto accountforepistemicuncertainty.account for epistemic uncertainty. NRC calculated kappa for each of three profiles separately.

Epistemic Uncertainty in Shear Modulus and Damping Sensitivity TestCurvesNRCSubmittalM1EPRI Rock: 0 -500 ftM1EPRI Rock: 0 -500 ftM2Linear &EPRI Rock Damping (~3%): 0 -500 ftM2Linear&EPRI Rock Damping (~3%): 0 -500 ftReference Rock at 1000 ftbelow control point. Reference Rock at 592 ftand 936 ftbelow control point for P1 and P4 filDepth Randomization, ln=0.2profiles.Depth Randomization, ln=0.2 Kappa and Epistemic UncertaintyNRCKappawascalculatedforeachbasecaseSubmittalKappacalculatedforvelocityprofilesP1P2Kappa was calculated for each base case profile.Kappa calculated for velocity profiles P1, P2, P3, P4, P5, and P6. Range of these kappas do not reflect epistemic uncertainty.ProfilekappaProfilekappa kappa (modified)P10.0120.012P20.0130.020(0.012 x1.68)Profilekappa BaseCase0.014LBC0.015()P30.0110.007(0.012 ÷1.68)P40.0130.013P50.0150.022(0.013 x1.68)UBC0.012P60.0120.008(0.013 ÷1.67)

AlifitiFtiAmplification FunctionsRock PGA = 0.3 g Comparison of Total Mean Soil Hazard by Spectral Frequency GMRS Comparison Primary Differences in Sensitivity TestVelocity profiles:TVA used two sets of 3-velocity profiles. The reference rock depthisat592ftinonecaseand936ftintheotherdepth is at 592 ftin one case and 936 ftin the other.NRC used three velocity profiles and depth of 1000 ftto reference rock.Low strain damping: BothTVAandNRCused~3%dampingintheupper500ft.Both TVA and NRC used 3% damping in the upper 500 ft. TVA used a factor of 1.68 about P1 and P4 total kappasto account for epistemic uncertainty. NRCcalculatedkappaforeachofthreeprofilesseparatelyNRC calculated kappa for each of three profiles separately.

Conclusions*GMRS are similar*Watts Bar screens in for risk evaluation*Control Point hazard curves similar at 10 HzandPGA,differat1HzHz and PGA, differ at 1 Hz-Due to different assumptions of depth to bedrock *Need additional information to support licenseeassumptionfordepthtobedrocklicensee assumption for depth to bedrock Browns Ferry Nuclear Power PlantiliIPEEE Screening EvaluationWeaknesses identified in IPEEE SER/TEReaessesdetedS/*Only low power injection systems selected-Did not include high pressure systems (HPCI/RCIC)gpy(/)-Not consistent with paths suggested in EPRI Np-6041 and other IPEEE submittals as "first line of defense" thatrespondsautomaticallythat responds automatically-Increases demand/reliance on low pressure systems*Automaticcircuitryfordepressurizationand*Automatic circuitry for depressurization and initiation of low pressure injection not included-Increases demand/reliance on operator actions/p Browns Ferry Nuclear Power PlantiliIPEEE Screening EvaluationConclusionConclusion*Based on weaknesses identified with the IPEEEtheIPEEEresultsarenotconsideredIPEEE, the IPEEE results are not considered adequate for screening purposesBFidiG2l*Browns Ferry is screened in as a Group 2 plant