ML14295A106

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October 22, 2014, Meeting Slide for Hydrology License Amendment Requests for Watts Bar Nuclear Plant
ML14295A106
Person / Time
Site: Watts Bar Tennessee Valley Authority icon.png
Issue date: 10/22/2014
From:
Watts Bar Special Projects Branch
To:
Tennessee Valley Authority
Hon A
References
Download: ML14295A106 (36)


Text

Hydrology License Amendment Requests Watts Bar Nuclear Plant October 22, 2014 1

Hydrologic Calculation Flow Chart 2

Hydrologic Calculation Flow Chart 3

Tennessee River SystemWattsBarWatts Bar Nuclear Plant Chattanooga Knoxville Wilson DamLargeandcomplexriversystem 4Large and complex river system Tennessee River System Overview Thorpe(N)Watauga South Holston Boone Ft. Patrick HenryClinch River Holston River French Broad RiverLittle Tennessee Bristol Projects (2)

NolichuckyNorris Melton Hill Cherokee DouglasFontanaNantahala (N)Thorpe (N)Santeetlah (T)ChatugeTellicoChilhowee(T)Calderwood (T)Cheoah(T)Watauga Wilbur HenryWttBFt. Loudoun Hiwassee River John SevierDoakes CreekWattsBarPlantTims Ford Raccoon Mountain Nottel yHiwassee Apalachia Blue RidgeOcoee 1, 2, 3Guntersville Nickajack Chickamauga W a tt s B a rDkRi Elk RiverWatts Bar PlantSequoyah PlantBrowns Ferry Plant NormandyTennessee-Tombigbee Waterway Wilson Wheeler Green RiverCumberland River D uc k Ri verBear Creek Projects (4)Pickwick KentuckyBarkley (C)Ohio River Note:(C) U.S. Army Corps of Engineers Dams(N)NantahalaPower & Light Company (subsidiary of Duke Energy)Beech River Projects (8) 5Mississippi River(T) Brookfield Smokey Mountain Hydro Power (Formerly Tapoco)

Main Stem Profile 813 813 741 682.5 634.5 595 556 507.7 414 359Summer Pool Elevations NOT TO SCALE 300 6 Historical Timeline of PMF1982 -1997TVA Dam Safety Modification Program Feb/March 2008 Bellefonte NOV & Hydrology model reconstitution project started September 2014Watts Bar LAR supplement1999 & 2001Watts Bar & Sequoyah UFSAR change reflect PMF reevaluation, respectivelyJuly & Aug 2012 WBN & SQN LAR submittal, respectively respectively 1997-1998 PMF r e-e v a l uated Dec 2009 HESCO 1979 & 1982 Sequoyah & Watts BarHydrologyAnalysis eeauated for TVA Dam Safety Mods barriers installed 2004TVA Reservoir 2013-2014 Dam Stabilit y Re p orts 7 Hydrology Analysis approved by NRC, respectively Operation Study completed yp Model Results WBN (Feet)()Original Licensing PMF Elevation738.11998 Calculation PMFElevation734.92012 LAR PMF Elevation739.2 2014 LAR HEC-RAS PMF Elevation738.92014 LAR Pro p osed Desi gnBasis PMF Elevation739.2 pg 8 Hydrologic Calculation Flow Chart 9

PMP Isohyets for 21,400 Square-Mile Event (Downstream Placement

)()10 PMP Isohyets for 7,980 Square-Mile Event Centered at Bulls Ga p, TN p, 11 Seasonal Variations of Rainfall (PMP)Anteceden t(in inches)Three-Day PMP(in inches)7,980-sq.mi.21,400-sq.mi.Dry IntervalbeforePMP7,980-sq.mi.21,400-sq.mi.MonthBasinBasinbefore PMP(days)BasinBasinMarch5.976.18317.0516.18April5.925.92316.9115.51May5.845.63316.6914.74June5.735.19316.3513.59July4.203.572-1/215.9812.46August4.203.622-1/215.9812.63 September4.464.122-1/217.0014.40 12Sources: March - Appendix G, CDQ000020080053Other values calculated using ratios in HMR-41 Table 7-7 Rainfall/Runoff Relationship DevelopmentUnchangedfrom2012LARRainfall-runoff relationships contained in the API method weredevelopedbytheUSWeatherBureau(USWB)inUnchanged from 2012 LAR were developed by the U.S. Weather Bureau (USWB) in the 1950s using procedures outlined in Kohler and Linsley'sUSWB Research Paper No. 34, Predicting the Runoff from Storm Rainfall, 1951.Therelationshipsweredevelopedfromstormandflood The relationships were developed from storm and flood records which relate precipitation excess to:-Basin rainfall-The week of the year-Location -API region Adiiiid(API) 13-A ntece d ent prec i p i tat i on i n d ex (API)

API BackgroundUnchangedfrom2012LARThe Antecedent Precipitation Index (API) method is currentlyusedbyTVARiverOperationsinforecastingUnchanged from 2012 LAR currently used by TVA River Operations in forecasting and was used by TVA in previous analyses of the TennesseeRiversystemfortheTVANuclearPower Tennessee River system for the TVA Nuclear Power Group.The API method is currentl y used b y TVA River yyOperations to accomplish their federally mandated, integrated operation of the TVA reservoir system which includes flood control responsibilitiesIn CDQ000020080052, the API method was ddddhd 14 compare d to two in d ustry stan d ar d met h o d s.

Computed API Prior to Main Storm 12The API for any day is equal to that of the previous day multiplied by 0.9, plus

an y rain on that da y 10 h esComputed API prior to main storm, 3.65 inches y yAdopted API prior to antecedent storm, varies API to demonstrate sensitivity 6 8 or API in Inc hComputed APIs are same atthis point; runoff in main storm not sensitive to ado p ted initial 4 ecipitation o pmoisture conditions beginningof storm 2 Pr e3-daydry periodmain stormantecedent storm 151234567891011Days LossMethod Comparisons 16 LossMethod Comparisons 17 SRO Hydrograph DevelopmentUnchangedfrom2012LARTVA FLDHYDRO computer code was used to develop surfacerunoff(SRO)hydrographsforallbasinsUnchanged from 2012 LAR surface runoff (SRO) hydrographs for all basinsCode used verified unit hydrographs, distributed rainfall, initial API and API region as inputsFLDHYDROoutputimportedtoExcelforprocessing FLDHYDRO output imported to Excel for processingBaseflowand initial soil moisture conditions were developed from long term TVA gage data 18 Inflow Hydrograph Routing 19 Hydrologic Calculation Flow Chart 20 Geometry DataOriginal cross sections were extracted from previous models and verifiedwithnewdataSeveraldatasourceswereusedto verified with new data. Several data sources were used to develop new profiles of the river channels. These include:Reservoir Reservoir-DTM/DEM Data-Corps of Engineers Bathymetric Survey bTri b utaries-DTM/DEM Data-Tennessee River Surve y (TRS) Ma p sy()p-USGS TopoMaps

-TVA Field SurveysFEMAModels 21-FEMA Models Geometry Data 22 HEC-RAS Steady-State Calibration -

1973 Flood Hi gh Water Marks615625HEC-RAS g595 605 L1973 Flood Profile575585Feet above MS L1973 High-Water Marks555565Elevation in River Bottom535 545River Bottom ElevationSteady-state model calibrated to observed high water marks 23525340350360370380390400410420430440450Tennessee River Mile HEC-RAS Unsteady-State CalibrationThis process calibrates reaches not influenced by RiOifh D 24 Reservo i r Operat i ons o f t h e D am HEC-RAS Unsteady-State CalibrationMinor differences in headwater elevation iDihdbd 25 us i ng Di sc harge as downstream b oun d ary Dam Rating CurvesUnchangedfrom2012LARChanges from FSAR to 2012 LARddiiUnchanged from 2012 LARRe d uce d max i mum open i ngsOrifice discharge coefficientsSubmergence effects

-referencedataforspillwayfreeflowused reference data for spillway free flow used-model data for orifice flow availableHESCO ConcertainersTurbine dischargeRimLeaks 26 Rim Leaks Watts Bar Rim LeaksUnchangedfrom2012LARUnchanged from 2012 LAR 27 Dam Rating CurvesChanges from 2012 LAR to 2014 LARCases added as a result of dam stability calculationsCasesaddedtoreflectpermanentdammodifications Cases added to reflect permanent dam modificationsNot all cases were used to support 2014 LAR 28 Flood Operational GuidesUnchangedfrom2012LARCapture reasonable dam operationsUnchanged from 2012 LARSimulate those operations in our modelRidfRiShdli(RS)R ev iew an d concurrence f rom Ri ver S c h e d u li ng (R v S) of the model dam simulation 29 Flood Operational Guide Curve to DRCUnchangedfrom2012LAR 780Combined Operating Guide and DRCtosimulatehowthedamUnchanged from 2012 LAR 760 770DRC to simulate how the dam operates during flood events 750 ter Elevation (ft)Gates Fully Open 740Headwa tTop of Gates Recover y Recovery Mode 730 Recovery Mode Base

Point y Mode ElbowDRC Curve-Spillway 30 7200100200300400500600700800900100011001200Discharge (1000 cfs

)

Unsteady Flow Rules*Water surface elevations at appropriate headwater/tailwatersectionsareextractedatthe headwater/tailwater sections are extracted at the beginning of each computational time stepItlbdflthtti

  • I n t erna l b oun d ary average fl ows over th e nex t ti me step are computed as a function of these elevations asprescribedintheFOG&DRCcalculations as prescribed in the FOG & DRC calculations 31 Unsteady Flow Rules Checking Tool 32 Model Setup*Combine the calibrated reservoirs into a composite HECRASmodel HEC-RAS model*Use of Inline/Lateral structures to connect each reservoir*Geometrymodificationsnecessaryforthecomposite
  • Geometry modifications necessary for the composite model are noted in the calculation 33 AssumptionsAssumptionFSAR2012 LAR2014 LARChickamaugaLock ConfigurationCurrent LockCurrent LockCurrent Lock Dallas Bay/Lick Branch/North

Chickamauga CrModeledas a rating curve at

Chickamauga

DamIncluded in the unsteady SOCH

modelIncluded in the unsteady HEC-RAS modelWtSddlDFilTtlFilTtlFilTtlFil(Ldt752ft)W es t S a ddl e D am F a il ure T o t a l F a il ure T o t a l F a il ure T o t a l F a il ure (L owere d t o 752 f ee t)West Saddle Dam RoutingModeledas a rating curve at Watts Bar DamDischargeseparated as a local in Yellow

CreekDischargeseparated as a local in Yellow Creek Correction for

Submergence The average tailwater rating curve used for

each event Correction for submergence was

performed for each

event Correction for submergence was performed for each eventDam ModificationsNot included HESCO Concertainers IncludedOperationalAllowancesNot includedEvaluatedfor each simulationEvaluatedfor each simulation 34Rim Leaks at Fort Loudoun, Watts Bar, and

NickajackNot includedIncludedIncluded AssumptionsAssumptionFSAR2012 LAR2014 LARMelton Hill ReservoirLevel pool routingUnsteady SOCH modelUnsteady HEC-RAS model Hiwassee River (mouth to HRM 18.9)Lag routedUnsteady SOCH modelUnsteady HEC-RAS modelMain Stem UnsteadyFlow ModelSOCHSOCHHEC-RASTributaryUnsteady Flow ModelTRBROUTETRBROUTEHEC-RASTurbineDischargeEvaluated for main river damsEvaluatedfor all dams with turbinesEvaluatedfor all dams with turbinesOperationalDeck/Gate

operability Not consideredIf operating deck was overtopped then the gates are assumed to

be inoperable on the If operating deck was overtopped then the gates are assumed to be inoperable on the recession siderecession sideDownstream Dams No failures assumedNo failures assumedNo failures assumed Loss Method A PI A PI A PI 35Norris Subbasins411Melton Hill Subbasins1011 Hydrologic Calculation Flow Chart 36